A photo shot and tweeted from the floor of the U.S. House of Representatives by U.S. House Rep. Katherine Clark shows Democratic members of the House staging a sit-in on the House floor "to demand action on common sense gun legislation" on Capitol Hill in Washington, United States, June 22, 2016.

House Speaker Paul Ryan had some harsh words for his Democratic colleagues on Thursday, following their sit-in.

"We are not going to let stunts like this stop us from carrying out the people's business," Ryan said at his weekly news briefing. "Why do I call this a stunt? Because it is one. Let's all be honest here."

"They are not trying to get this done through regular order," he said. "They're staging protests; they're trying to get on TV; they are sending fundraising solicitations."

"If this is not a political stunt, they why are they trying to raise money off of it?"

On Wednesday, Democrats staged a sit-in, trying to persuade the Republican majority in Congress to take up votes on gun control measures in response to last week's mass shooting in Orlando, Florida, the deadliest in modern U.S. history.

The Democrats ended the sit-in at around midday on Thursday.

—Reuters contributed to this report.