There have been chaotic scenes in the lower house of the US Congress as Democrats staged a sit-in to demand a vote on gun control legislation.
The protest comes in the wake of the recent shootings in Orlando, the deadliest in modern US history.
Republicans adjourned the House early on Thursday to try to quash the sit-in, switching off the TV cameras.
But some Democrats remained, streaming speeches live via phones despite breaking rules on broadcasting.
The transmissions via Periscope and Facebook Live were taken up by the C-Span network, which provides continual coverage of Congress. One Democratic congressman, Scott Peters, who provided a feed, said the sit-in was breaking rules anyway.
The Democrats' protest follows the gun attack on 12 June, when a man claiming allegiance to the so-called Islamic State group, Omar Mateen, killed 49 people at the Pulse club in Orlando, Florida.
Entrenched divide: Anthony Zurcher, BBC North America
Depending on one's perspective, the sit-in was either a shameless publicity stunt in advance of a dangerous piece of legislation or the purest expression of democracy and civil disobedience since the 1960s.
But as Democrats chanted, waved signs and sang in protest, there was no debating it was a historic break with congressional traditions that has little precedent in modern times.
The display seems unlikely to alter the dynamic in a House dominated by conservatives overwhelmingly opposed to new gun regulations. If anything, after a night of sniping and rancour across the partisan divide, the two sides may be even more deeply entrenched.
Republicans view the use of the terrorist watch list to prevent firearm purchases as giving the government the power to suspend due process with next to no judicial oversight. Democrats counter that it is a common-sense first step towards addressing rampant gun violence.
Both see their position as guided by principles to be defended to the end, a prospect that makes this dispute likely to be settled only at the ballot box in November.
By Wednesday evening, some 168 House Democrats (out of 188) and 34 senators (out of 44) were on the floor of the House, some literally sitting on it.
As the protest reached its 10th hour, Speaker Paul Ryan tried to restore control with a recess.
He 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.
Some Democratic representatives brought in sleeping bags, pillow and blankets, others doughnuts for colleagues.
After a brief adjournment, the House resumed business at 02:30, with the majority Republicans voting through a number of bills, but granting no vote on gun control.
They then called an adjournment until after 4 July, reminding lawmakers that transmitting images and video broke House rules.
But Democrats shouted their new campaign slogan "No bill, no break!" and some remained on the floor, streaming speeches live. Representative Eric Swalwell told the BBC that the lawmakers would stay through the night.
Associated Press reported that about 16 lawmakers remained at 06:30, including House Minority Leader Nancy Pelosi.
She said: "Just because they cut and run in the dark of night, just because they have left, doesn't mean we are taking no for an answer."
The BBC's Laura Bicker in Washington says the protest follows years of Democrat frustration at being unable to pass stricter gun control measures.
She says that although 100 bills have gone before Congress in the past five years and all have failed, this is an election year and Democrats are making it clear to the electorate that if they want change, they know which way to vote in November.
'Tears of grief'
The sit-in is being led by congressman John Lewis, a veteran of the civil rights movement of the 1960s.
"What has this body done [to respond to the violence]?'' Mr Lewis asked.
"Nothing. We have turned a deaf ear to the blood of innocents. We are blind to a crisis. Where is our courage? How many more mothers... and fathers need to shed tears of grief?"
President Barack Obama took to Twitter to thank Mr Lewis "for leading on gun violence where we need it most".
Republicans dismissed the protest as a publicity stunt.
Representative Kevin Cramer said: "I have no objection to them making fools of themselves on TV."
Paul Ryan told CNN he would not bring a gun-control vote in the House.
"They know that we will not bring a bill that takes away a person's constitutionally guaranteed rights without... due process," he said.