WASHINGTON -- Republicans attempting to end a virtually unprecedented sit-in on the House floor by Democrats demanding votes on gun control measures brought the chamber back into session early Thursday about an hour-and-a-half after the previous day's session was ended.

They forced a vote that wound up with passage of a GOP-sponsored measure providing funds to fight the Zika virus outbreak, then pushed through a vote adjourning the House until July 5.

The Republican strategy of adjourning the chamber until after the July 4 holiday to shut Democrats down was denounced furiously by Democrats as "cowardly."

Get Breaking News Delivered to Your Inbox

Adjournment came with the sit-in roughly 16 hours old.

Afterwards, 21 Democratic members remained on the floor. Democratic Leader Nancy Pelosi was among them, alternately addressing them and conferring with other members. About a dozen staffers were in the room.

In an interview with "CBS This Morning" early Thursday, Democratic National Committee chairwoman Rep. Debbie Wasserman Schultz, D-Florida, said that House Democrats will continue to stage their sit-in even despite the adjournment.

"We are going to hold the floor of the House of Representatives -- we are in our nineteenth hour -- until we can get the majority to do their jobs and get us a vote," she said. "It is a cowardly act that they have not at least allowed a vote."

The only person on the Republican side was Speaker Paul Ryan's communications director, Brendan Buck, who was by himself, watching the proceedings.

As the sit-in was going on, a crowd of several hundred gun control advocates gathered outside the Capitol and cheered as Democratic lawmakers addressed them.

Image from video provided by House Television shows House Speaker Paul Ryan at podium attempting to bring House back in order late on night of June 22, 2016 as Democrats stand up from sit-in to hold up signs with names of mass shooting victims House Television via AP

Democratic leadership had urged members to vote "no" on the $1.1 billion in Zika funding because of anti-contraceptive provisions in the bill, because it doesn't fully fund President Obama's $1.9 billion request, and because it takes money from other programs to provide much of the funding.

Sources think the legislation the House OK'd has more of an uphill climb in the Senate.

The measure is actually a compromise crafted by Republican leaders in both chambers.

At one point during the extraordinary sit-in, rebellious House Democrats shouted down Ryan when he attempted to restore order late Wednesday night.

The stunning and unruly scene was broadcast live to the world from Democrats' cell phones, feeds picked up by C-SPAN after Republicans shut down the network's cameras.

The sit-in was well into its 10th hour, with Democrats camped out on the floor stopping legislative business in the House, when Ryan stepped to the podium to gavel the House into session and hold votes on routine business. Angry Democrats chanted "No bill, no break!" -- referring to a planned week off ahead of the July 4th holiday -- and waved pieces of paper with the names of gun victims, continuing their protest in the well of the House even as lawmakers voted on a previously scheduled and unrelated measure to overturn a veto by President Obama.

Ryan attempted to ignore the outbursts and announce the business of the day, pounding down his gavel over shouting.

Democrats yelled "Shame! Shame! Shame!" But Ryan left the lectern and the voting continued. Then Democrats began singing "We Shall Overcome," still holding up the names of gun victims.

The scene presented a radical, almost shocking departure from the normal orderly conduct of the House.

As the night stretched on Republicans signaled plans to push through a bill to deal with the Zika outbreak and then adjourn until after July 4 to shut Democrats down, a plan Democrats furiously denounced as "cowardly".

Republicans hoped to present themselves as soberly attending to business and Democrats as disruptive.

Democrats said they would stay until Republicans yielded to their demands to hold votes on bills to strengthen background checks and prevent people on the no fly list from getting guns in the wake of last week's massacre in Orlando, Florida.

"Are they more afraid than the children at Sandy Hook?" asked Rep. Mike Thompson, D-Calif., referring to the 2012 shooting that killed 26 people, including 20 elementary school children, in Newtown, Connecticut. "What is so scary about having a vote?"

Rep. John Lewis, a veteran civil rights leader, asked what Congress has done, then answered his own question: "Nothing. We have turned a deaf ear to the blood of innocents. We are blind to a crisis. Where is our courage?"

Ryan dismissed the protest as "nothing more than a publicity stunt," and in an interview with CNN, made clear there would be no guns vote.

"We're not going to take away a citizen's constitutional rights without due process," he said.

The protest began around 11:30 a.m., interrupted briefly when Rep. Ted Poe, R-Texas, tried to start the House's work at noon. The customary prayer and Pledge of Allegiance went ahead, but Poe was forced to recess the House when dozens of Democrats refused to leave the well.

By evening, 168 House Democrats - out of 188 - and 34 Senate Democrats joined the protest, according to the House minority leader's office. One after another, they spoke of the need for gun control and talked of constituents who had been killed.

Scattered around the House floor were signs reading "Disarm Hate." Visitors watched from the galleries.

About an hour into the chaos on the House floor Wednesday night, Democrats started repeating, "Why would you let terrorists buy a gun?"

Rep. Louie Gohmert, R-Texas, came up to Democrats on the floor and began shouting, repeatedly saying that "radical Islam killed these people, ISIS killed these people."

Congress remains gridlocked over gun control, a divide even more pronounced in a presidential election year. The sit-in had the feel of a 1960s-style protest, as some lawmakers sat on the floor, others in their seats.

Republicans had staged a similar protest in 2008. Democrats controlling the House at the time 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 Nancy Pelosi sent the House on its August recess. Pelosi ordered the cameras turned off.

C-SPAN, a cable and satellite network that provides continual coverage of House and Senate floor proceedings, does not control the cameras. They're run on authorization by legislative leaders.

Although the cameras were turned off Wednesday, lawmakers relied on social media to transmit video, using Facebook, Twitter and Periscope. C-SPAN broadcast live video streamed on Periscope and Facebook from lawmakers' accounts. Democrats posted the Capitol's main telephone number, which was overwhelmed, and urged constituents to call and request a vote. They also encouraged tweeting under the hashtag #NoBillNoBreak.

Democratic senators joining the protest included Minority Leader Harry Reid, Bernie Sanders, I-Vt., and Chris Murphy, D-Conn., who had waged a nearly 15-hour filibuster last week to force votes in the Senate on gun legislation. Those votes failed Monday night.