US Democrats staged a rare sit-in Wednesday in the House of Representatives, demanding that the Republican-led body vote on gun-control legislation following the Orlando nightclub massacre.

"We have to occupy the floor of the House until there is action," Democratic Congressman John Lewis, a civil rights icon who marched with Reverend Martin Luther King Jr in the 1960s, said before he and dozens of colleagues sat down on the carpeted well of the chamber.

The dramatic action came just as the House presiding officer moved to declare the body in recess.

US lawmakers, mainly Democrats, have introduced several bills aimed at reducing gun violence, including legislation to expand background checks -- a provision that has broad support among the voting public. No such bill has passed Congress.

"It's a shame that you need to go to extraordinary measures like this," Congresswoman Karen Bass told MSNBC in a telephone interview just off the House floor as the sit-in continued.

"I think we will be here until they decide to take up the vote."

House Speaker Paul Ryan has refused to schedule a vote for gun control legislation in the aftermath of the Orlando shooting that left 49 people dead.

The chamber was scheduled to wrap up its business Thursday before going on its vacation ahead of the Fourth of July holiday.

"If there's no bill to vote on, there should be no congressional break," Democrat Earl Blumenauer told the House.

Earlier this week, the US Senate voted on four gun control amendments -- two from Democrats and two from Republicans -- after Senate Democrat Chris Murphy delivered a 15-hour floor speech demanding votes on gun control.

The Senate rejected all four measures, but lawmakers crafted a bipartisan compromise bill aimed at preventing terror suspects and people on no-fly lists or FBI watchlists from buying a firearm.

The bill's sponsors said Senate leaders assured them a vote on the legislation.

Murphy walked to the House to express solidarity with those conducting the sit-in there.

"You cannot stand down at a moment of peril for this country," he told MSNBC.