The Congress has been blocked by a Democrat protest over a vote on gun control legislation.
The Democrats’ sit-in comes in the wake of the recent shootings in Orlando, the deadliest in modern US history.
Republican Speaker Paul Ryan tried to regain control of the lower house but was met with chants of “no bill, no break!”
The Republicans switched off the House TV cameras but Democrats continued to feed live pictures via their phones.
The transmissions, broadcast by the C-Span network, technically break House rules, but one Democrat representative, Scott Peters, who provided a feed via the Periscope app, said the sit-in was breaking rules anyway.
The Democrats’ protest follows the gun attack on June 12, when a man claiming allegiance to ISIS, Omar Mateen, killed 49 people at the Pulse club in Orlando, Florida.
On June 22, some 168 House Democrats – out of 188 – and 34 senators – out of 44 – were on the floor.
As the protest reached its 10th hour, Paul Ryan tried to restore control with a recess, and then a return to voting on other legislative business.
Paul Ryan banged his gavel and tried to ignore the outbursts but amid Democrat shouts of “Shame! Shame!” he left the podium.
Democrats began singing “We shall overcome” and held up the names of gun attack victims.
The floor of the House became chaotic, with Republicans and Democrats shouting at each other.
Some Democratic representatives brought in sleeping bags, pillow and blankets, others doughnuts for colleagues.
Outside Congress, several hundred gun-control advocates gathered to voice support for the Democrats, shouting “hold the floor” and “do your job”.
A motion for a brief adjournment was passed at about 01:30 local time and the House then resumed at 02:30, with the majority Republicans hoping to vote on a bill on the Zika virus and then adjourn fully to July 5.
The sit-in is being led by congressman John Lewis, a veteran of the civil rights movement of the 1960s.
President Barack Obama took to Twitter to thank John Lewis “for leading on gun violence where we need it most”.
Paul Ryan dismissed the protest as a publicity stunt.
He told CNN he would not bring a gun control vote in the House of Representatives.
“They know that we will not bring a bill that takes away a person’s constitutionally guaranteed rights without… due process,” Paul Ryan said.
Some senators are pushing for a compromise, with top Democratic Senator Harry Reid supporting a Republican proposal.
Harry Reid said he supported new legislation proposed by Republican Senator Susan Collins that would stop gun sales to a limited number of people who are on some terrorism watch lists.
The bill is due to come before the Senate on June 23.
Plans to tighten gun controls in the US, including the restriction of weapons sales to people on terrorism watch lists have been rejected by the Senate.
Four proposals were brought before the Senate after 49 people were shot dead in Orlando attack on June 12.
However, Democratic and Republican senators voted along party lines, blocking each other’s bills.
Senators strongly disagreed about how to prevent more attacks happening in future.
Republican Senator John Cornyn said: “Our colleagues want to make this about gun control when what we should be making this about is the fight to eliminate the Islamic extremism that is the root cause for what happened in Orlando.
“My colleagues in many ways want to treat the symptoms without fighting the disease.”
Photo NBC News
Democratic Senator Barbara Mikulski said: “Why is it we would go through such incredible scrutiny to board an airplane to protect me against terrorist, and yet we have no scrutiny of the people on the terrorist watch list to be able to buy a gun?”
Republicans and members of the National Rifle Association (NRA) complained that the bills put forward by the Democrats violated the constitutional right to bear arms. They are concerned that without enough “due process”, law-abiding Americans wrongly named on watch lists would be prevented from buying weapons.
Democrats said the Republican proposals were too weak.
Eight days before the Senate’s vote on June 20, Omar Mateen shot 49 people dead and injured many more in the worst mass shooting in recent US history.
Omar Mateen was a US citizen who had been known to the FBI since 2013 but was not on a terrorism watch list.
In the US, gun dealers are licensed by the federal government. People can be prevented from buying weapons if they have mental health problems or are guilty of serious crimes, but there is no specific prohibition for those on the terrorism watch list. There are currently about one million people on that list.
There are other ways to buy guns – at gun shows, or from a private vendor online – that do not require any background checks.
The Senate voted down legislation that would have closed a gun show loophole and expanded background checks to cover private sales.
It also rejected a bill to ban suspects on terrorism watch lists from buying guns, a bill (backed by the NRA) that would allow the US attorney general to delay a gun purchase by a known or suspected terrorist, but prosecutors would need to convince a judge of the would-be-buyer’s connection to terrorism within three days and a bill that would alert the FBI to terrorism suspects who have purchased a gun, without blocking the purchase outright.