The House of Representatives erupted into chaos on Wednesday night as Speaker Paul Ryan attempted to regain control of the chamber. The move came 10 hours into a sit-in led by House Democrats over Republicans’ refusal to consider gun control measures in the wake of the Orlando terror attack, the largest mass shooting in U.S. history.

Ryan’s words were inaudible as Democrats repeatedly shouted “Shame!” and “No bill, no break!” toward him and other Republicans as members voted on an unrelated and highly unusual late-night veto override intended to force Democrats into order.

It did not. As Republicans began to leave the chamber, almost all of the Democrats who were present before the vote stayed put. Some went home at around 11 p.m., but most vowed to remain through the night.

The Democrats remained committed to following each other’s lead as it neared midnight and as the speeches pushing for a vote on gun control measures continued. The House was gaveled back into session at around 1:00 a.m. and again at 2:30 a.m. for votes on a Zika virus funding bill. With tensions still running high, House Minority Leader Nancy Pelosi told her members that they could either stay on the floor, or return in the morning for a whip meeting.

California Rep. Maxine Waters vowed to stay on the floor, encouraging her colleagues to do the same: “You’ve gone this far, you’ve been this strong,” she said. At that point it was a waiting game to see who stayed and who left. Most exited the chamber, leaving no more than 20 Democrats participating in the sit-in by 4:00 a.m.

The events inside the chamber Wednesday were unprecedented in modern American politics. For hours, Missouri Rep. Emanuel Cleaver sat in a chair holding a striped pillow. Illinois Rep. Jan Schakowsky got comfortable on the ground, leaned against a chair, and covered herself with a blanket.

For much of the day, the sit-in, which began at 11:30 a.m., was not viewable on C-SPAN. Republican leaders quickly ordered the House into recess after it began and, in accordance with House rules, the cameras are off when it is not formally in session.

But at around 2 p.m., C-SPAN began broadcasting various Democratic House members’ live Periscope feeds from the House floor. Reps. Mark Takano and Scott Peters livestreamed the entire sit-in on their phones—a violation of House rules when in session.

Members of the public sitting in the galleries were cheering throughout the afternoon and late into the night, applauding as Democrats continued to chant and raise pieces of paper displaying the names of victims of gun violence, in addition to banners showing the faces of the Orlando victims. Pelosi hurried up and down the chamber’s rows, checking in with members as the unprecedented disruptions continued.

Rep. John Lewis, the civil rights icon who spearheaded the effort, remained seated on the floor next to a lectern even as Ryan gaveled the body into session.

Lewis and his Democratic colleagues are demanding that Republicans allow votes on legislation that would expand background checks for firearm sales and prohibit suspected terrorists from purchasing guns. Four similar amendments fell short in the Senate on Monday.

The proposal to prohibit persons placed on terror watch lists from buying guns—called “no fly, no buy” has prompted GOP concerns about infringing on due process rights.

Speaking from the floor during the sit-in, democratic Rep. Seth Moulton said due process concerns should not be an excuse to block every gun control-related proposal.

“If there are problems with the no fly list, then let’s fix it,” Moulton said. “But tell me this, if they are so many problems on the no fly list, then why do we have it?”

Ryan did end up calling a vote—but not about gun control measures. Over the two votes on unrelated matters—the first about a Labor Department fiduciary rule—the House settled into a bizarre process. Members recorded their votes, but shouting Democrats remained in the well while Republicans—most stone-faced and clearly annoyed—kept to their side of the floor, talking among themselves.

Lewis finally got to his feet. The crowd of Democrats began singing a version of “We Shall Overcome,” adapting the second chorus to the events of the night: “We shall pass a bill someday.”

One of the most heated exchanges came when firebrand conservative Rep. Louie Gohmert of Texas approached the Democrats, finger pointed, yelling, “Radical Islam killed these people.” A Democrat could be heard responding: “Why do you want to let terrorists buy a gun?”

Earlier, as the sit-in extended into the evening, the atmosphere among Democrats in the House got another boost of energy as they learned that a crowd of supporters was gathering outside the Capitol building. Later, those protesters chanted “Do your job” to exiting GOP representatives.

The sit-in’s stalwarts included Rep. Tammy Duckworth—an Iraq war veteran and U.S. Senate candidate in Illinois—DNC Chair Debbie Wasserman Schultz, Minority Whip Steny Hoyer, and Maryland Rep. Elijah Cummings.

Wasserman Schultz read aloud a letter from former Rep. Gabrielle Giffords in support of her protesting colleagues. (Giffords left her House seat after being critically wounded in a shooting in 2011.)

Nearly all the Democrats’ speeches included stories of constituents who had been killed by gun violence. Some of the speakers represented districts where the nation’s most tragic mass shootings have taken place, including Newton’s Rep. Elizabeth Esty.

Reporters packed the House Press Gallery as chaos unfolded below. By 8 p.m., around 90 members were on the floor, many of them huddled around a lectern as one of their colleagues spoke. Nearly everyone stood and cheered as Lewis made his way through the crowd to take his place at the lectern.

Lewis was defiant from the start.

“Thank you for getting in trouble,” he began, to resounding cheers. Even the members of the public in the gallery above shouted their approval—just another of the many House rules flouted throughout the night.

Many of the Democrats mentioned the need to put their sit-in “in context”—perhaps an attempt to counter GOP criticism that it was a stunt to drum up support in an election year.

The Democrats acknowledged that any proposals on gun control measures were unlikely to be approved by the GOP-controlled House. But Democrats could still reap political benefits. A vote would force Republicans to take a public stance on gun control, during a week in which a CNN/ORC poll showed a vast majority of Americans supports “no fly, no buy” and expanded background checks.

Lewis described the sit-in in the context of his work during the civil rights movement.

In his dramatic speech, Lewis said the sit-in was “another bridge” in a reference to the “Bloody Sunday” march over the Edmund Pettus Bridge in Selma, Alabama, 1965.

“When we come back in July, we will start all over again,” Lewis said before departing around 4:00 a.m. Thursday morning.