Katherine Clark was tired of the moments of silence. After each mass shooting, legislators would file solemnly onto the floor of the U.S. House of Representatives, proclaim their immense sadness and frustration over the latest tragedy, and bow their heads—then do nothing. That “grisly routine,” as the congresswoman calls it, repeated yet again after the massacre at the Pulse nightclub in Orlando in June, the deadliest in American history. Republicans refused to allow a vote on legislation with overwhelming public support: a bill to close a loophole on background checks, and another forbidding people on the FBI’s terrorism watch list from buying guns.

“That’s all we have are these moments of silence,” Clark, a Democrat who represents Massachusetts’s 5th congressional district, told the New Republic. “The absolute refusal to bring forth two commonsense bills that are pro–Second Amendment and can help stem the incredible wave of gun violence we’re seeing in this country; they’re bipartisan, and commonsense, and we couldn’t even get them up for a vote.”

Clark took her frustration to Representative John Lewis, the civil rights icon from Georgia. He suggested they “try something dramatic,” and together they led a sit-in on the House floor. Republicans ignored the action and shut off C-SPAN’s live feed, which the Democrats worked around by broadcasting live to social media. The sit-in lasted more than 24 hours, drawing 170 legislators in the House chamber and a large crowd of supporters outside the Capitol Building.

“This was something that had really captured the attention not only of the American people, but across the globe,” said Clark, calling it “an incredible moment of pride” for the Democrats. “It was an extraordinary moment.”

It was—albeit an unsuccessful one, if the goal was to force a vote on the two gun bills. But compared to the usual milquetoast behavior of Congress, the spectacle was almost revolutionary. And it wasn’t the first time Clark had taken such a bold stand. A former prosecutor, she made national news during the Gamergate controversy in 2015, when she launched a crusade against internet trolls—calling on the FBI and Department of Justice to investigate and prosecute online harassment, and sponsoring several bills to address the problem. More recently, she was just the second of more than 60 members to announce she would boycott Donald Trump’s inauguration. Instead, she spent the day meeting with the Planned Parenthood League of Massachusetts. The next day she was back in the capitol for the Women’s March on Washington.