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.
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.