Religious studies lecturer Mohammad Hanif said there was a deafening explosion and “everyone in the halls was screaming for help”.
1TV News quoted the health ministry as saying that 24 of the wounded were severely injured.
Afghan President Ashraf Ghani condemned the “terrorist attack”.
The president declared November 21 a day of national mourning, with the flag to be flown at half mast.
The UN mission in Afghanistan tweeted: “UNAMA outraged by #Kabul bombing when communities across #Afghanistan are marking day of special religious significance. Credible reports of heavy civilian casualties. UN human rights teams establishing facts. UN family extends deepest condolences to the many families affected.”
Pakistan’s PM Imran Khan condemned the “cowardly act of terrorism” and sent his condolences to the bereaved families.
The Islamic State in Afghanistan group, sometimes known as Islamic State Khorasan, has claimed responsibility for most of the recent deadly attacks of this kind.
It said it was behind two attacks in Kabul in August that killed dozens of people.
The Taliban have also continued attacks, although many of them target security forces.
A Taliban spokesman, Zabiullah Mujeed, has denied the group had any involvement in November 20 attack.
Veteran US photojournalist David Gilkey and his Afghan translator Zabihullah Tamanna have been killed in Helmand province in southern Afghanistan.
David Gilkey of National Public Radio (NPR) and Zabihullah Tamanna were travelling with the Afghan army when they came under fire and their vehicle was hit by a shell, NPR said.
The attack also killed the driver of the vehicle, an Afghan soldier.
Two other NPR employees travelling with David Gilkey and Zabihullah Tamanna were unharmed, the radio network said in a statement.
The vehicle David Gilkey, 50, and Zabihullah Tamanna, 38, were travelling in was struck by shellfire near the town of Marjah, NPR said.
Zabihullah Tamanna was a photographer and journalist in Afghanistan, as well as a translator.
Michael Oreskes, senior vice president at NPR, paid tribute to the photographer.
He said: “David has been covering war and conflict in Iraq and Afghanistan since 9/11. He was devoted to helping the public see these wars and the people caught up in them. He died pursuing that commitment.
“As a man and as a photojournalist, David brought out the humanity of all those around him. He let us see the world and each other through his eyes.”
David Gilkey is the first US journalist outside the military to be killed in the conflict in Afghanistan.
He received a series of awards during his career, including a 2007 national Emmy for a video series about US Marines from Michigan serving in Iraq.
In 2011, David Gilkey was named still photographer of the year by the White House Photographers’ Association, one of nine first-place awards he received from the body.
His work on an investigation into veteran medical care and his coverage of the Ebola crisis helped secure awards for NPR.
In 2015, David Gilkey received the Edward R. Murrow Award for his coverage of international breaking news, military conflicts and natural disasters.
Sgt Bowe Bergdahl will face a general court-martial for desertion and other charges.
The US soldier was held for five years by the Taliban in Afghanistan.
General Robert Abrams overruled a previous recommendation that the case be moved to a lower court with a maximum penalty of 12 months of prison.
Sgt Bowe Bergdahl now could be sentenced to life in prison if found guilty.
He was released in exchange for five Taliban officials held at Guantanamo Bay, Cuba, in 2014.
The 29-year-old gave the first public account of his story last week to the podcast Serial.
The podcast ran excerpts of an interview, in which Bowe Bergdahl claims that he left his base without permission in order to create a crisis and highlight poor leadership within his unit.
Bowe Bergdahl’s release, initially cheered by President Barack Obama and other officials, quickly became controversial when critics said it ran contrary to policy against negotiating with terrorists.
With news that the recommendation had been disregarded, his lawyer Eugene Fidell sent an email to reporters on behalf of the defense team saying he “had hoped the case would not go in this direction”.
In the same email, Eugene Fidell called upon leading Republican presidential candidate Donald Trump to “cease his prejudicial months-long campaign of defamation against our client”. Donald Trump has in the past accused Bowe Bergdahl of treason.
Eugene Fidell also asked members of the House and Senate Armed Services Committees to “avoid any further statements or actions that prejudice our client’s right to a fair trial”.
Five Guantanamo detainees were swapped for the soldier, when Bowe Bergdahl was freed in May 2014. He had spent almost five years in Taliban captivity, after he walked off his post in Afghanistan in 2009.
Republicans on the House Armed Services Committee accused President Barack Obama of misleading them over the prisoner swap.
The charges were filed against Bowe Bergdahl in March, and his case was recommended for the lower court in October.
The US has launched a “full investigation” into airstrikes that killed 19 people at a Medecins Sans Frontieres-run Afghan hospital on October 3, President Barack Obama.
According to the US military, a strike targeting Taliban in the northern city of Kunduz may have caused “collateral damage”.
Offering his “deepest condolences”, President Barack Obama said he expected a “full accounting of the facts” and would then make a definitive judgement.
At least 12 MSF staff members and seven patients were killed in the incident.
The UN called the strikes “inexcusable and possibly even criminal”, with Secretary General Ban Ki-moon calling for a thorough and impartial investigation.
“International and Afghan military planners have an obligation to respect and protect civilians at all times, and medical facilities and personnel are the object of a special protection,” said UN High Commissioner Ra’ad Al Hussein Zeid.
The hospital, run by the medical charity Medecins Sans Frontieres (Doctors Without Borders), was severely damaged by a series of strikes lasting more than an hour from 02:00 local time on October 3. Dozens were also injured in the attack.
MSF president Meinie Nicolai described the incident as “abhorrent and a grave violation of international humanitarian law”.
“All indications currently point to the bombing being carried out by international Coalition forces,” MSF said.
A spokesman for US forces in Afghanistan, Col. Brian Tribus, said on October 3 that US forces had conducted an air strike in Kunduz “against individuals threatening the force” at the same time.
He added: “The strike may have resulted in collateral damage to a nearby medical facility.”
President Barack Obama expressed his “deepest condolences” for the deaths in a White House statement.
He added: “The Department of Defense has launched a full investigation, and we will await the results of that inquiry before making a definitive judgment as to the circumstances of this tragedy.”
MSF nurse Lajos Zoltan Jecs was sleeping at the facility when it was hit.
“It was absolutely terrifying,” he said.
He saw a fellow nurse “covered in blood, with wounds all over his body”, a statement issued by MSF said.
Lajos Zoltan Jecs and other staff went outside when the bombing stopped.
“What we saw was the hospital destroyed. We tried to take a look into one of the burning buildings. There are no words for how terrible it was. In the intensive care unit six patients were burning in their beds.”
The Afghan interior ministry said a group of 10 to 15 militants had been hiding in the hospital.
The Taliban denied that any of its fighters were there.
A Taliban statement described the air strikes which hit the hospital as “deliberate”, and carried out by “the barbaric American forces”.
There has been intense fighting in Kunduz since Taliban fighters swept into the northern city on September 28.
On July 29, Afghanistan’s secret services have confirmed that Taliban leader Mullah Mohammad Omar has been dead for two or three years in a Pakistani hospital, although this has not been confirmed by the Taliban.
Mullah Omar was a reclusive figure even before his Taliban government was driven from power in late 2001 and he was forced into hiding – very few images of him exist.
There have been several reports in the past that Mullah Omar had died.
A statement purporting to be from Mullah Omar was released in July backing peace talks with the Afghan government. The last audio message thought to be from him appeared in 2006 but even this was leaked and not meant for public consumption.
In April 2015, the Taliban published a biography of Mullah Omar, saying he was alive and still supreme leader of the movement, as he had been since 1996.
Taliban say Mullah Omar was born in 1960 in the village of Chah-i-Himmat, in Kandahar province.
He fought in resistance against Soviet occupation in 1980s, suffering a shrapnel injury to his right eye.
He also forged close ties to al-Qaeda leader Osama Bin Laden.
Mullah Omar became “supreme leader” of Taliban movement in 1996.
US-led forces overthrew his government in 2001; US state department has a $10 million bounty on him.
The biography says he does not own a home and has no foreign bank account, and saying he “has a special sense of humor”
The Afghan Taliban have published a surprise biography of the reclusive Mullah Mohammed Omar, to mark his 19th year as their supreme leader.
The 5,000-word biography on their main website clarifies disputed facts about his birth and upbringing.
It lists his favorite weapon – the RPG 7 – and says he leads a simple life and has a “special” sense of humor.
It says Mullah Omar, whose whereabouts were unknown, “remains in touch” with day-to-day Afghan and world events.
The US state department has a $10 million bounty on Mullah Omar, who has not been seen since the US-led invasion of Afghanistan in 2001.
It was Mullah Omar’s backing for al-Qaeda leader Osama Bin Laden that sparked the campaign.
It is unclear why the Taliban have chosen the 19th anniversary of his supreme leadership to publish the biography but some analysts say it may be an attempt to counter the growing influence of Islamic State in Afghanistan.
Commentators and Taliban watchers have been unable to agree on many facts about Mullah Omar, including his birth and heritage.
The biography says he was born in 1960 in the village of Chah-i-Himmat, in the Khakrez district of Kandahar province, in the south of the country.
It refers to the supreme leader as Mullah Mohammad Umar “Mujahid” and says he is from the Tomzi clan of the Hotak tribe.
It says his father was Moulavi Ghulam Nabi, a “respected erudite and social figure” who died five years after Mohammed Omar’s birth. The family moved to Uruzgan province.
The biography says Mullah Omar abandoned his studies in a madrassa school after the Soviet forces invaded Afghanistan and became a jihadist “to discharge his religious obligation”.
It lists his military feats fighting the Russians between 1983 and 1991, saying he was wounded four times and lost his right eye.
In 1994, Mullah Omar took over leading the Islamic mujahideen to tackle the “factional fighting” among warlords that followed the collapse of the communist regime in 1992.
Then in 1996 he was conferred the title “ameer-ul-momineen” (head of the pious believers), the biography says, becoming supreme leader.
After taking Kabul and establishing the Islamic Emirate of Afghanistan, the biography tells of the “arrogant infidel powers of the world” who “could not tolerate Sharia law” and launched a joint military invasion.
In a section on his “charismatic personality”, the biography says Mullah Omar is tranquil and does not lose either temper or courage, does not own a home and has no foreign bank account and is affable, has a special sense of humor and never considers himself superior to his colleagues.
In a section entitled His daily activities in the present circumstances, the biography says: “In the present crucial conditions and regularly being tracked by the enemy, no major change and disruption has been observed in the routine works of [Mullah Omar].”
It says he “keenly follows and inspects the jihadi activities against the brutal infidel foreign invaders” adding: “He remains in touch with the day-to-day happenings of his country as well as the outside world.”
The US military has paid tribute to Major General Harold Greene, shot dead by an Afghan soldier in an insider attack on Tuesday.
Gen. Harold Greene, the most senior US soldier killed in action overseas since Vietnam, was shot dead as he visited a UK-run military training facility.
Afghan President Hamid Karzai said the shooting was a “cowardly attack”.
Officials said the Afghan soldier who opened fire in the insider attack had been shot dead.
Insider attacks have become one of the defining features of the later phase of the conflict in Afghanistan.
They have hampered efforts to train the country’s 350,000-strong security force as they prepare to take on the Taliban once most US and NATO forces depart.
Gen. Harold Greene is the most senior US soldier killed in action overseas since Vietnam
Tuesday’s attack is the most high profile.
Along with Gen. Harold Greene, at least 15 other soldiers were injured.
Two British, several Americans and generals from Germany and Afghanistan were among the wounded.
US Army spokesman Juanita Chang described Gen. Harold Greene as a “true hero”.
She said he was working “to better advance the Afghans and the cause in Afghanistan”.
“He really believed what he was doing over there,” she said.
Gen. Harold Greene was a technology expert described by the New York Times as playing a key role in integrating smartphones, video conferences “and even virtual worlds into military culture”.
The newspaper said that his last promotion of his 30-year army career came earlier this year when he was deployed to Afghanistan to oversee the military handover from American to Afghan control as US forces begin withdrawing from the country.
Correspondents say that the attack raises new doubts about NATO’s ability to train Afghan forces as Western countries gradually withdraw.
The Pentagon described “insider attacks” as a “pernicious threat”.
From the end of this year just under 10,000 American troops will remain, with all withdrawing by the end of 2016.
The Pentagon described it as an isolated attack and insisted that there has been no breakdown of trust between coalition soldiers and their Afghan counterparts.
The Afghan soldier who opened fire was recruited three years ago.
He carried out the shootings from a guard post at a large group of senior Afghan and international troops.
By the time he had emptied the magazine of his US-issue M16 rifle, more than a dozen people had been shot, our correspondent says.
The Afghan commander of the British-led officers’ academy, Gen, Gulam Sakhi, was among those wounded.
A US general has been killed in an attack by a man in Afghan military uniform at British-run Camp Qargha near Kabul, US officials say.
Fifteen others have been injured. Half of them are thought to be Americans and they also include a German general.
Afghanistan’s Ministry of Defense said the Afghan soldier was shot dead after he opened fire.
The major-general is the most senior international soldier killed since the fall of the Taliban in 2001.
The attacker was a soldier who was recruited three years ago.
The US general has been killed in an attack by an Afghan soldier at Camp Qargha near Kabul
The incident is said to have occurred late morning or lunchtime after a dispute between Afghans and an armed Afghan soldier.
The Afghan soldier opened fire from a guard post at a large group of senior Afghan and international troops.
By the time he had emptied the magazine of his US-issue M16 rifle, more than a dozen people had been shot, our correspondent says.
The Afghan commander of the British-led officers’ academy, General Gulam Sakhi, was among those wounded, and German military sources said a German general was also hit. At least one British soldier was also wounded.
The training academy is modeled on UK military academy Sandhurst and will be the only British military presence in Afghanistan when operations end this year.
The NATO-led International Security Assistance Force (ISAF) said in a statement: “We can confirm that an incident occurred involving local Afghan and ISAF troops at Camp Qargha.
“The camp, also known as the Kabul ANA Officer Academy, is an Afghan National Security Forces facility. We are in the process of assessing the situation.”
The academy is set in a long, low ridge of hills close to Kabul.
Its military history syllabus includes the analysis of Afghan tactics in past wars against the British, as well as during the mujahedeen wars against the Soviet army.
There were 10,000 applicants who applied ahead of its first intake.
Shortly after the academy opened there was a shooting incident when an Afghan soldier in a neighboring barracks opened fire, injuring Australian and New Zealand troops providing security.
There are also troops from other nations at the site, including a large contingent of US soldiers.
Sgt. Bowe Bergdahl is expected to submit to questioning next week by the US Army general probing the circumstances that led to the his 2009 capture by the Taliban, his attorney said on Tuesday.
Freed prisoner of war Bowe Bergdahl was introduced to the investigating officer, Major General Kenneth R. Dahl, and is expected to be questioned by him next week in Texas in an informal setting, said the soldier’s lawyer, Eugene Fidell.
“They’ve said hello to one another. It was literally a meeting to introduce themselves to one another,” said Eugene Fidell, a military law expert who lectures at Yale University.
Bowe Bergdahl was released in May in exchange for five Taliban prisoners who were transferred to Qatar from the Guantanamo Bay US prison in Cuba.
Bowe Bergdahl was introduced to the investigating officer, Major General Kenneth R. Dahl, and is expected to be questioned by him next week in Texas in an informal setting
Critics have questioned whether the Obama administration paid too high a price and whether Bowe Bergdahl had deserted his combat outpost in Afghanistan before his capture.
Bowe Bergdahl, 28, has completed counseling and a reintegration program and been assigned a desk job at a Texas military base as the Army investigates events that led to five years of imprisonment by captors whom Eugene Fidell has described as ruthless killers.
Eugene Fidell is to advise Bowe Bergdahl during the session with the Army general probing the case, and Kenneth R. Dahl is expected to have his own legal counsel present as well, he said.
The investigation was to be completed 60 days from the time of Kenneth R. Dahl’s appointment on June 16 but an extended deadline may be needed, Eugene Fidell said.
“There may be an extension in this case. It’s a complicated matter with a lot of witnesses,” he said.
A senior Army officer has said the purpose of the probe was to determine facts and circumstances surrounding Bowe Bergdahl’s disappearance up to the point of capture.
Kenneth R. Dahl’s finding and recommendations will be presented to the director of Army staff, who is not bound by the conclusions and who could issue his own determinations and recommendations.
Eugene Fidell said Bowe Bergdahl, of Hailey, Idaho, is to remain under the Army’s authority pending the outcome of the inquiry.
According to the UN refugee agency, the number of people forced to flee their homes because of war or persecution exceeded 50 million in 2013, the first time since World War Two.
The overall figure of 51.2 million is six million higher than the year before, a report by the United Nations High Commissioner for Refugees (UNHCR) says.
Conflicts in Syria, central Africa and South Sudan fuelled the sharp increase.
Of particular concern are the estimated 6.3 million people who have been refugees for years, sometimes even decades.
People living in what the UN terms “protracted” refugee situations include more than 2.5 million Afghans. Afghanistan still accounts for the world’s largest number of refugees, and neighboring Pakistan is host to more refugees than any other country, with an estimated 1.6 million.
The number of people forced to flee their homes because of war or persecution exceeded 50 million in 2013, the first time since World War Two (photo UNHCR)
Around the world, thousands of refugees from almost forgotten crises have spent the best part of their lives in camps. Along Thailand’s border with Burma, 120,000 people from Burma’s Karen minority have lived in refugee camps for more than 20 years.
Refugees should not be forcibly returned, the UN says, and should not go back unless it is safe to do so, and they have homes to return to. For many – among them the more than 300,000 mainly Somali refugees in Kenya’s Dadaab camp – that is a very distant prospect.
Some camps, the UN refugee agency admits, have become virtually permanent, with their own schools, hospitals, and businesses. But they are not, and can never be, home.
The world’s refugees are far outnumbered by the internally displaced (IDP) – people who have been forced to flee their homes, but remain inside their own countries.
In Syria alone there are thought to be 6.5 million displaced people. The conflict has uprooted many families not once but several times. Their access to food, water, shelter and medical care is often extremely limited, and because they remain inside a conflict zone, it is hard for aid agencies to reach them.
Worldwide, the UN estimates there are now 33.3 million internally displaced people.
Large numbers of refugees and IDPs fleeing to new areas inevitably put a strain on resources, and can even destabilize a host country.
Throughout the Syrian crisis, Lebanon, Jordan and Turkey have kept their borders open. Lebanon now hosts more than a million Syrian refugees, meaning a quarter of its total population is Syrian. The pressure on housing, education and health is causing tensions in a country which itself has a recent history of conflict.
The UN is concerned that the burden of caring for refugees is increasingly falling on the countries with the least resources. Developing countries are host to 86% of the world’s refugees, with wealthy countries caring for just 14%.
Despite the fears in Europe about growing numbers of asylum seekers and immigrants, that gap is growing. Ten years ago wealthy countries hosted 30% of refugees, and developing countries 70%.
The US army has opened an investigation into the circumstances surrounding Sgt. Bowe Bergdahl’s disappearance from an Afghan outpost.
Major General Kenneth Dahl, who served in combat in Afghanistan, has been appointed to lead the investigation.
Sgt. Bowe Bergdahl, 28, returned to the US after five years in captivity on Friday.
Shortly after his release, several commentators and soldiers came forward to brand him a deserter and call for him to be punished.
Sgt. Bowe Bergdahl returned to the US after five years in captivity
The Pentagon has previously concluded Sgt. Bowe Bergdahl walked off base in Paktika province without authorization, but officials have not determined whether he intended to desert.
Bowe Bergdahl was flown from a military hospital in Germany to Brooke Army Medical Center in Texas on Friday, where he will complete the final phase of the reintegration process.
He was released by the Taliban in late May in exchange for five Guantanamo Bay detainees, a move that has been criticized by some lawmakers.
In a statement, the defense department said Maj. Gen. Kenneth Dahl would have access to evidence gathered in 2009 shortly after Sgt. Bowe Bergdahl was captured.
But officials will not be able to interview him until a team working on his “reintegration” will allow it.
“We ask that everyone respect the time and privacy necessary to accomplish the objectives of the last phase of reintegration,” the department said in a statement, adding there is no timeline for wrapping up the investigation.
On Friday, Maj. Gen. Joseph DiSalvo said Bowe Bergdahl “looked good” as he returned to Texas and was in uniform and saluted.
Sgt. Bowe Bergdahl had not yet been in contact with his family, which officials described as his own choice.
Sgt. Bowe Bergdahl, who was freed last month after five years in Taliban captivity, is in a stable condition in hospital in Texas, officials have said.
Sgt. Bowe Bergdahl, 28, arrived in the US from Germany early on Friday and was taken to a military medical center for the next part of his reintegration.
He “looked good”, was in uniform, and saluted, Maj. Gen. Joseph DiSalvo said.
Bowe Bergdahl has not yet been in contact with his family, which officials described as his own choice.
“He appeared just like any sergeant would when they see a two-star general – a little bit nervous,” Gen. Josepg DiSalvo said.
“But he looked good, saluted, and had good deportment.”
Bowe Bergdahl has not yet been in contact with his family, which officials described as his own choice
Bowe Bergdahl arrived at about 01:40 local time and was subsequently driven in a three-vehicle convoy to Brooke Army Medical Center at Fort Sam Houston.
Army officers also said Bowe Bergdahl had not yet been in contact with his parents, Robert and Jani Bergdahl, who are not in Texas.
“Family support is a critical part of the reintegration process,” Army psychologist Col. Bradley Poppen said.
“Overall, though it is a returnee’s choice to determine when, where and who they want to re-engage with socially, and I believe the family understands that process at this point in time.”
In the near future, Bowe Bergdahl will work with medical staff on reintegration, the progress of which will be driven by the soldier himself.
“There is no set timeline,” Joseph DiSalvo said.
The focus of reintegration will be on re-equipping the soldier, who is staying in a hospital room, with an “appropriate level of mental and physical stability to effectively resume normal activities with minimal physical and emotional complications”, he said.
Col. Bradley Poppen said: “What we are trying to do is get him to recognize that the coping skills he used to survive this long, five-year ordeal may not be healthy and functional now.”
Bowe Bergdahl has not yet been made aware of the media coverage of the circumstances of his disappearance from a military base in Afghanistan in 2009 nor of the controversy over the deal that saw him exchanged for five senior Taliban commanders held at Guantanamo Bay, Cuba.
“Anything surrounding the controversy of his disappearance is not part of his reintegration,” Gen. Joseph DiSalvo said.
Shortly after Bowe Bergdahl’s release, several commentators and soldiers came forward to brand him a deserter and call for him to be punished.
Critics of the prisoner swap, which include some Democrats, have objected to the fact Congress was not given notice of the deal. They say the Taliban detainees are too dangerous to free.
The Pentagon has concluded he left his post in Paktika province without authorization but it is unclear if he intended to desert. The Army has said it will investigate the circumstances of his capture, leaving open the possibility he could be prosecuted for misconduct.
An Army review of the matter will take place after Sgt. Bowe Bergdahl’s treatment has finished, officials said.
Sgt. Bowe Bergdahl will return to the US on Friday, officials have said.
Bowe Bergdahl, 28, will fly to a military medical centre in Texas for the next part of what the military calls a “reintegration mission”.
Officials previously said he would be reunited with his family there.
Sgt. Bowe Bergdahl was freed on May 31 in exchange for five Taliban commanders held at Guantanamo bay, a deal criticized by the Republicans.
He has been recuperating at a military hospital in Germany since his release.
Sgt. Bowe Bergdahl will return to the US on Friday
Critics of the prisoner swap, which include some Democrats, have objected to the fact Congress was not given notice of the deal, and they say the detainees are too dangerous to free.
Shortly after his release, several commentators and soldiers came forward to brand him a deserter and call for him to be punished.
The Pentagon has concluded he left his post in Paktika Province without authorisation but it is unclear if he intended to desert from the Army. The Army has said it will investigate the circumstances of his capture, leaving open the possibility he could be prosecuted for misconduct.
His family has received death threats and a welcoming party in his hometown in the state of Utah was cancelled amid safety concerns.
Sgt. Bowe Bergdahl has not made any public comment since his release, but on Thursday, the Daily Beast website published a letter it said was one of two the soldier sent to his parents during his captivity through the International Red Cross.
In the letter, Bowe Bergdahl says he left because conditions were deteriorating at the base.
Excerpts of Bowe Bergdahl’s journals sent to a friend before he went missing, published by the Washington Post, suggest a young soldier struggling to handle the mental stress of war.
US army officials are investigating the reported friendly-fire incident in southern Afghanistan that killed five American soldiers and two Afghans.
Rear Admiral John Kirby said the US had “reason to suspect that friendly fire is the cause here, specifically friendly fire from the air”.
He said the Pentagon “would let investigators do their work”.
Afghan officials say coalition forces had called for air support to fend off a Taliban attack in Zabul province.
An Afghan soldier and an interpreter were killed in the incident.
US army officials are investigating the reported friendly-fire incident in southern Afghanistan that killed five American soldiers and two Afghans
On Tuesday, White House press secretary Josh Earnest said President Barack Obama had been informed of the deaths and that his thoughts and prayers were with the families of those killed.
The incident is among the most serious cases of so-called “friendly fire” in Afghanistan, US military sources confirmed on Tuesday.
NATO-led troops have been battling Taliban and other insurgents in the country since 2001. Militants have stepped up attacks as foreign combat troops leave this year.
US defense officials told the Associated Press news agency the Americans killed were special operations forces.
Those elite troops are responsible for calling in air support. Under constraints imposed by President Hamid Karzai, they may only do so when they fear they are about to be killed, after concerns over civilian deaths.
The ISAF force currently has soldiers from 50 contributing nations in Afghanistan. Most troops stationed in the south are American.
The incident happened in Arghandab district, a place hotly contested between the Taliban and international forces for some years.
There have been more than 30 NATO forces killed this year in Afghanistan – the latest incident is the deadliest so far in 2014.