Revolt in the House of Representatives turned raucous overnight, with protesting Democrats shouting down Speaker Paul Ryan's attempts to restore order during a gun-control protest that stretched into its 18th hour.
Earlier, Republicans branded the move as a publicity stunt before summarily adjourning the chamber until after the Fourth of July.
The stunning and unruly scenes were broadcast live to the world from Democrats' cellphones, feeds which were picked up by C-SPAN after Republicans shut down the network's cameras.
Democrats took over the floor of the House at 11:25 a.m. ET Wednesday, demanding Republican leadership schedule votes on bills about universal background checks and blocking gun sales to those on no-fly lists.
At 4:30 a.m. ET Thursday, roughly a dozen remained sitting on the House floor.
A crowd of gun-control advocates also remained gathered outside the Capitol into the early morning.
Democrats nearly drowned out Ryan's words with chants when the House Speaker first reconvened the session for a vote on a matter unrelated to the gun issue at around 10 p.m. ET Wednesday.
Some held pictures of mass shooting victims in view of the cameras. Ryan attempted to ignore the outbursts and announce the business of the day, pounding down his gavel.
"The chair appreciates that members will differ on matters of policy and will seek to express those differences," Ryan said over the loud chants. "But the chair would hope that the business of the House could be conducted in a fashion that respects positively on the dignity and decorum of this institution."
Democrats — who were shown solidarity by senators dropping by for support — broke out into a rendition of "We Shall Overcome" with the words "We shall pass a bill, someday."
As Ryan left the chair, they chanted: "Shame! Shame!"
In what was essentially an attempt to cut short the protest, Republicans who control the chamber reconvened at around 2:30 a.m. ET Thursday to fresh chants of "no bill, no break."
They held a number of procedural votes that allowed the House to wrap up the legislative session until July 5.
While the House formally adjourned at 3:13 a.m. — and the House cameras turned off — the Democrats showed no signs of abandoning the sit-in.
A new video stream on the Periscope app showed Minority Leader Nancy Pelosi decrying how Republicans "left in the dark of night." She praised her Democratic colleagues for "taking us to a new place" in the gun-control debate.
On the floor of the House, Pelosi read from a letter by Gabby Giffords, the former U.S. representative who survived a 2011 mass shooting, written after British lawmaker Jo Cox was gunned down on June 16.
"Now is not a time for lawmakers to retreat to their ideological corners and do nothing," Pelosi read. "It's a time to stand shoulder-to-shoulder with the American people to make responsible changes that honor our history and our diversity, and make our country a safer place to live."
The revolt in the House comes amid Democrats' efforts to pursue gun-control legislation following the shooting at a gay nightclub in Orlando that killed 49 people.
Rep. John Lewis, an icon on the civil rights movement, led the protest as the hashtag #NoBillNoBreak quickly climbed to the top of Twitter's trending topics. He drew the comparison between the gun-control fight and the fierce desegregation battle in the South in the 1950s and 1960s.
"A little more than 50 years ago, I crossed a bridge not just one time, but it took us three times to make it all the way from Selma to Montgomery," he said during a brief press conference after adjournment, referring to the pivotal civil rights marches in Alabama that helped shift public opinion in favor of civil rights nationwide in 1965. "We have other bridges to cross."
Earlier, Lewis argued the need for change in the wake of the Orlando massacre.
"The question is whether we are accepting a new sense of normal," he said. "That should not be normal for people to be enjoying their lives on a Sunday morning, and the next thing they know they're blown away ... That can never be normal, and we should not allow it to be normal."
Lewis was one of dozens to give impassioned speeches on the floor of the House as the sit-in stretched on.
House Speaker Ryan early on dismissed the sit-in a publicity stunt, while House Majority Leader Kevin McCarthy told NBC News' Luke Russert that the Democrats' were engaging in "political antics."
Rep. Kevin Cramer, a Republican representing North Dakota, also balked at the protest.
"I, frankly, don't mind voting every day against a bill that would take away Second Amendment rights from folks," he said.
Republican lawmakers also tried to match #NoBillNoBreak with their own hashtag — #StopTheStunt — but with less success than the Democrats.
Strong words were exchanged between some Republicans and Democrats on the floor.
Rep. Louie Gohmert, R-Texas, got into a heated argument with Democratic Rep. Corrine Brown of Orlando.
The pair pointed fingers at each other's faces and Gohmert yelled "radical Islam killed these people, and you know it!"
The sit-in comes a week after Senate Democrats waged a nearly 15-hour filibuster demanding votes on gun control bills.
Votes were held Monday, and four gun policy measured failed to pass the 60-vote threshold in the Republican-controlled Senate.
"During the '60s, the sit-in started with 3 or 4 people and it spread like wildfire. This will spread," Lewis told NBC News early in the protest. "We're going to sit in, sit down, stand up ... We're going to be here for a while."
While dramatic, the Democrats' moves were was not unprecedented.
Republicans staged similar protest in 2008. Democrats who controlled the House at the time also turned off the cameras amid a GOP push for a vote to expand oil and gas drilling. Republicans occupied the floor, delivering speeches after then-Speaker Pelosi sent the House on its August recess.