Gas masks, a prayer and guns drawn. Inside the riot at the U.S. Capitol Building

The U.S. House of Representatives was already on edge when a Capitol police officer halted proceedings Wednesday afternoon and loudly told lawmakers that they might need to crawl beneath their chairs.

Then a series of bangs rang out as the doors to the chamber were sealed. Police told the politicians to find their gas masks.

And in the distance, someone said a prayer.

Already an unprecedented afternoon in the nation’s capital, an acrimonious debate in Congress over whether to accept the results of Joe Biden’s win in the November election devolved into chaos Wednesday as a pro-Trump mob forced its way into Capitol Hill and clashed violently with police.

A woman was shot inside the Capitol Building, where she was pronounced dead, according to multiple reports. Officers were injured and tear gas was deployed in the Capitol Building as a political effort to undermine democracy gave way to a violent attempt to overrun it.

“This is what an attempted coup looks like,” said U.S. Rep. Debbie Wasserman Schultz, a Democrat from Broward County, who spoke to the Miami Herald over the phone from Washington.

The rush on Congress — declared a riot by police — began after throngs that had gathered to hear Trump speak moved toward Capitol Hill, where they clashed with police, surrounded the building and then broke in as the House and Senate debated whether to accept the results of the presidential election in Arizona.

Inside the House of Representatives chamber, a Miami Herald reporter heard police officers bar the door from the inside and tell everyone to remain in place. The proceedings were halted for about two minutes.

“We had breach of the Capitol building, that’s why we ordered a lockdown of both chambers, the House and Senate,” a Capitol Police lieutenant announced. “We will advise of further information as it becomes available. Please do not try to leave.”

For a moment, the hearing began again, with Republicans divided over whether to reject Biden’s Arizona electors. Then police made a second announcement: “Be prepared to get under your chairs if necessary.”

From the third floor, as rioters began to roam the halls of the Capitol, a Miami Herald reporter could hear police tell everyone to lie face down on the floor. Gas masks were distributed as a precaution. Tear gas had been deployed in the rotunda, police said. A loud bang — possibly a gun firing — could be heard.

Inside, officers pushed a table against the doors to use as a barricade and, crouching behind it, drew their firearms. Someone banged on the doors and broke a pane of glass. A face peered through the opening at officers, who had their guns drawn.

Oklahoma Rep. Markwayne Mullin, a former mixed martial arts fighter, took off his suit jacket and stood next to the police and attempted to tell the rioters to leave. They didn’t.

The evacuation was calm, with House members and staff escorted down the stairs on the west side of the chamber to the basement of the Capitol, followed by reporters, past a group of people in police custody lying on the ground.

Members of Congress on the third floor were taken to a room in Longworth House office building. Reporters were led to the cafeteria in the basement of Longworth. A group of Democratic lawmakers noted that Republican elected officials were the fastest to leave the chamber when ordered to do so by Capitol Police.

“Did you notice it was the Republicans who left the fastest?” said Rep. Susan Wild, D-Pa.

While leaving, Orlando-area U.S. Reps. Val Demings and Darren Soto walked together. Soto, wearing an American flag mask, asked how reporters were doing.

Demings offered her own take on the situation, with a smile: “They can’t stop us.”

Pictures later emerged of rioters milling about the floors of the Senate chambers, one of them wrapped in a Trump flag. One man stood at the podium where only moments earlier Vice President Mike Pence had been presiding over the proceedings.

The FBI said two suspected explosive devices were investigated and “rendered safe.”

“What happened today at the Capitol is disgraceful and un-American,” said U.S. Sen. Rick Scott, who had indicated Wednesday that he planned to vote to reject electors from the state of Pennsylvania, as Trump wanted. “It is not what our country stands for.”

At a press conference late Wednesday afternoon, D.C. police chief Robert Contee said the district’s Metropolitan Police Department was called in “hours ago” by the Capitol Police Department as backup in the effort to clear out the Capitol. Contee confirmed that “multiple” Metropolitan Police Department officers were injured by rioters in the process, and were being treated. The department was “still engaged in the fight to regain control of the Capitol,” he said.

“Attacking our Capitol and the selfless law enforcement officers defending it is as unpatriotic and appalling as it gets,” said U.S. Rep. Brian Mast, a Jupiter Republican and military veteran who, minutes before the riot reached the chamber, tried to question Pelosi’s acceptance of Arizona’s electors from the House floor.

Democratic U.S. Rep. Charlie Crist, a former Republican Florida governor, tweeted that Trump should be removed from office through the 25th Amendment, in which the vice president and a majority of Cabinet members can declare a president “unable to discharge the powers and the duties of the office.”

Biden addressed the nation from Delaware and called on Trump “to fulfill his oath, to defend the Constitution, to go on television now and demand an end to this siege.” Trump then released a video calling on his supporters to go home, though he repeated that the election was stolen. He did not specifically condemn the takeover or the violence.

A number of Democrats and Republicans compared the scene to political turmoil in developing nations.

Republican U.S. Sen. Marco Rubio said the assault on the Capitol looked like “third-world style, anti-American anarchy.”

“There is nothing patriotic about what is occurring on Capitol Hill,” he tweeted.

Around 6 p.m., Trump tweeted “these are the things and events that happen,” and “Go home with love & in peace. Remember this day forever!” The tweet was removed by Twitter minutes later.

Congress was expected to reconvene Wednesday evening.

In a phone interview, Wasserman Schultz, the Broward County Democrat, said she was reminded of a scene a year ago in Venezuela when opposition leader Juan Guaidó was blocked from entering the country’s National Assembly by a mob attempting to interfere with the country’s democratic proceedings on behalf of strongman Nicolás Maduro.

Trump, she said, had instigated the mob by claiming fraud without evidence and stoking anger over the results of a legitimate election.

“It’s sickening. It’s sickening,” she said. “This is supposed to be the greatest country on earth, the safe haven to which others fleeing violence and atrocity in other countries can find their safe haven. We’ve lost all credibility.”

Miami Herald reporter Samantha Gross contributed to this report.