They - members of Congress, staff members and more - were hiding under tables, hunkered in lockdowns, saying prayers, and seeing the fruits of the country's divisions up close and violent.

Guns were drawn. A woman was shot and killed. A Trump flag hung on the Capitol. The graceful Rotunda reeked of tear gas. Glass shattered.

The pro-Trump mob took over the presiding officer's chair in the Senate, the offices of the House speaker, and the Senate dais, where one yelled, "Trump won that election."

They posed for photos in the office of House Speaker Nancy Pelosi, one with his feet propped on her desk, another sitting in the same seat Vice President Mike Pence had occupied only moments before during the proceedings to certify the Electoral College vote.

This began as a day of reckoning for President Donald Trump's futile attempt to cling to power as Congress took up the certification of President-elect Joe Biden's victory. It devolved into scenes of fear and agony that left a prime ritual of American democracy in tatters.

Trump told his morning crowd at the Ellipse that he would go with them to the Capitol, but he didn't. Instead he sent them off with incendiary rhetoric.

"If you don't fight like hell, you're not going to have a country anymore," he said. "Let the weak ones get out," he went on. "This is a time for strength."

His lawyer, Rudy Giuliani, told the crowd, "Let's have trial by combat."

What happened Wednesday was nothing less than an attempted coup, according to Democrat representative Diana DeGette, while Republican Senator Ben Sasse, a frequent Trump critic, said: "Today, the United States Capitol - the world's greatest symbol of self-government - was ransacked while the leader of the free world cowered behind his keyboard."

Authorities eventually regained control, as night fell, and Congress resumed its process of confirming Biden's Electoral College win.

Shortly after 2pm, Republican Senator Chuck Grassley of Iowa and Vice President Mike Pence were escorted from the Senate as protesters and police shouted outside the doors.

Police evacuated the chamber at 2.30pm, grabbing boxes of Electoral College certificates as they left

Heavily armed officers brought in as reinforcements started using tear gas in a coordinated effort to get people moving toward the door, then combed the halls for stragglers, pushing the mob farther out onto the plaza and lawn, in clouds of tear gas, flash-bangs and percussion grenades.

Democrat Scott Peters said security officers urged members to put gas masks on and herded them into a corner of the massive room.

"When we got over to other side of the gallery, the Republican side, they made us all get down, you could see that they were fending off some sort of assault, it looked like," he said. "They had a piece of furniture up against the door, the entry to the floor from the Rotunda, and they had guns pulled." The officers eventually escorted the lawmakers out of the chamber.

Some members remained in the upper gallery seats, and ducked on the floor as police secured a door to the chamber down below with guns pointed.

Describing the scene, Democratic representative Jim Himes of Connecticut said "there was a point there where officers had their guns and weapons pointed at the door, they were obviously expecting a breach through the door. It was clear that there were pretty close to pulling the trigger so they asked us all to get down in the chamber."

llinois Representative Mike Quigley was also in the balcony. "It's not good to be around terrified colleagues, with guns drawn toward people who have a barricade ... people crying."

As he walked out of the Capitol, Himes said Democrats had known for years that US democracy was in peril, and hopefully this was its worst moment.

"But with a president egging these people on, with the Republicans doing all they can to try to make people feel like their democracy has been taken away from them even though they're the ones doing the taking, it's really hard, really sad. I spent my entire political career reaching out to the other side. And it's really hard to see this." he said."

Australian Associated Press