An eight-storey building collapsed in the Bangladeshi capital, Dhaka, killing at least 70 people and injuring other 200, government officials say.
Many more people are feared trapped after building collapse and frantic efforts are under way to rescue those beneath the debris.
The army is helping with the rescue operation on the outskirts of Dhaka.
Building collapses are common in Bangladesh where many multi-storey blocks are built in violation of rules.
The eight-storey building contained a clothing factory, a bank and several other shops. It collapsed during the morning rush hour.
Many people have gathered near the scene looking for friends and relatives.
It is not yet clear what caused the collapse but local media reports said a crack was detected in the block on Tuesday.
An eight-storey building collapsed in the Bangladeshi capital, Dhaka, killing at least 70 people and injuring other 200
Rescue workers are using concrete cutters and cranes to dig through the rubble.
Local police chief Mohammad Asaduzzaman told the Reuters news agency that factory owners appeared to have ignored a warning not to allow their workers into the building after the crack was detected.
Police told local media that the rear of the building suddenly started to collapse on Wednesday morning and within a short time the whole structure – except the main pillar and parts of the front wall – had caved-in, triggering panic.
Only the ground floor of the Rana Plaza in Sava remained intact after the collapse, officials said, as army and fire service rescuers equipped with concrete cutters and cranes dug through rubble to pull out trapped people. Many onlookers also joined the effort using their bare hands.
Survivors have described their terror as the collapse began.
“I was in the cutting section of the garment factory and suddenly we heard a huge noise and the building collapsed within a few minutes,” a garment worker told private Somoy TV.
“I removed the rubble and came out with two other workers. But at least 30 other workers in my cutting section were still unaccounted for,” he said.
In November, a fire at a garment factory in a Dhaka suburb killed at least 110 people and triggered a public outcry about safety standards in the industry.
The last major building collapse was in 2010, when a four-storey building collapsed in Dhaka killing at least 25 people and injuring several others.
Bangladesh has one of the largest garment industries in the world, providing competitively priced clothes for major Western retailers which benefit from its widespread low-cost labor.
Following November’s fire, Western retail chains who buy from factories in Bangladesh urged factory owners to improve safety standards.
More than 200 people are now known to have died in a fire at a garment factory in Karachi, Pakistani police have said.
Many others were injured in the blaze. It began on Tuesday night, hours after a factory fire killed 23 in Lahore.
Correspondents say that the Karachi blaze is one of the worst industrial accidents in the country’s history.
Some 40 firefighting vehicles were needed to tackle it, officials said. Rescuers are still recovering bodies.
The cause of both fires are being investigated. Reports say that both may have been caused by faulty electricity generators.
Medical officials said victims in both fires mostly died of suffocation, while others were burned alive as the infernos took hold.
More than 200 people are now known to have died in a fire at a garment factory in Karachi
In Karachi, the building was still smouldering on Wednesday as rescuers pulled out the bodies of those who were killed. Officials said the number of dead had now risen to 212.
Karachi fire chief Ehtesham Salim said: “We found people who died because of suffocation caused by the highly toxic smoke. They died first and then their bodies were burned by the raging fire.”
Workers had little time to escape from the four-storey building – many could do so only by jumping from the windows. At least 65 employees are reported to have suffered from broken bones.
As the full horror of the blaze unfolded overnight, shouting and sobbing relatives of trapped workers scuffled with police as rescuers battled to save people still thought to be trapped in the building.
Chief Fire Officer Ehtishamud Deen said that his staff was trying to rescue about 20 people trapped in the basement and on the fourth floor.
Workers spoke of panic and confusion as the fire spread.
“It was terrible, suddenly the entire floor filled with fire and smoke and the heat was so intense that we rushed towards the windows, broke its steel grille and glass and jumped out,” Mohammad Saleem told AFP in hospital.
“I fell on the ground and it was extremely painful, I saw many people jumping out of windows and crying in pain for help,” he said.
Speaking at the scene, Karachi official Mohammad Hussain Syed said that the scale and severity of the fire made it difficult to find and identify the dead.
“Some bodies are completely charred and cannot be recognized,” he said.
“It is only possible [to identify them] through DNA tests. It was a big garment factory where lots of people were working. That’s why it is difficult to assess how many have come out safely and how many failed to escape and were trapped.”
“The condition of the building is very bad now.”
Bodies have been taken to several different hospitals, and police are still compiling a definitive list of casualties. Police said that they feared more bodies could be inside the building.
Firefighters said that the poorly ventilated factory had no fire exits or alternative means of escape and that most of the dead had been suffocated by toxic smoke.
Officials said windows at the factory were blocked with metal grilles and that it was crammed with combustible materials including piles of clothes and chemicals.
Firefighters on crane lifts are now trying to reach through windows of the gutted building to rescue trapped survivors, all suffering from burns and smoke inhalation.
The cause of the blaze was still being investigated, police said, but workers say it too may have been caused by a faulty generator.
Garments factories across Pakistan require their own power sources because of increasingly erratic national grid electricity supplies.
The industry is critical to Pakistan’s frail economy – according to central bank data, it provided 7.4% of Pakistan’s GDP in 2011 and employed 38% of the manufacturing sector workforce, accounting for 55.6% of total exports.