Five days after supporters of President Donald Trump stormed the US Capitol, new videos are revealing the level of violence that left lawmakers cowering inside and police howling for backup.

The footage spilling out on social media shows a policeman dragged out and beaten on the ground; protesters chanting to "hang" Vice President Mike Pence; and a pack of demonstrators appearing to search for high officials inside the building.

The videos, which have steadily flowed out onto the internet since the January 6 unrest, show Trump's supporters as much more aggressive and violent than the footage seen that day.

"We came close to half of the House nearly dying on Wednesday," said Democratic representative Alexandria Ocasio-Cortez, calling it an "insurrection against the United States."

Five people did die on Capitol Hill that day: a police officer reportedly hit in the head with a fire extinguisher; a protester shot inside the Congressional main building by police as she tried to break down a door; and three other protesters of "medical emergencies" during the melee.

Another Capitol Police officer reportedly killed himself four days after the attack. It is unknown if the two events were linked.

Supporters of President Donald Trump violently attacked police during the siege of the US Capitol
Supporters of President Donald Trump violently attacked police during the siege of the US Capitol AFP / ROBERTO SCHMIDT

Early videos showed a boisterous crowd press their way, without particular coordination, past police to barge into the Capitol.

But the newest footage shows organized groups among the larger mob, many wearing military assault-style uniforms, attacking outnumbered police en masse with flagpoles, batons, hockey sticks and chemical sprays. One person attacked the officers with a crutch.

In another video, an officer cries out in pain when he is crushed between two swinging doors as protesters push in from one side and police push back. One protester tried to wrench off the officer's gas mask.

With many of the protesters known to belong to armed militia groups, and after two pipe bombs were discovered at nearby buildings, police and lawmakers saw a serious threat.

"I have talked to officers who have done two tours in Iraq and say that this was scarier to them than their time in combat," said Washington police chief Robert Contee.

Participants in the storming of the US Congress came with helmets, gas masks, shields and climbing gear
Participants in the storming of the US Congress came with helmets, gas masks, shields and climbing gear AFP / Joseph Prezioso

One target of the crowd's ire was Pence, who had rejected Trump's pressure to halt proceedings in Congress that day that would confirm Joe Biden -- and not Trump -- as the clear winner of the November 3 election.

"Mike Pence didn't have the courage to do what should have been done to protect our Country and our Constitution," Trump tweeted as the protesters descended on the Capitol.

The buildings were ordered to lock down, and as the vice president was whisked to secret, secure premises inside the Congress complex, outside, a video shows, the crowd chanted, "Hang Mike Pence."

Inside, video shows men decked out in combat gear carrying many plastic zip-tie handcuffs, suggesting they hoped to seize elected officials.

Lawmakers took cover: House Speaker Nancy Pelosi described how they barricaded doors, turned off lights and hid under tables for two and a half hours before the crowd was brought under control.

Capitol Police Chief Steven Sund said the threat was clear from the beginning.

"As soon as they hit the fence line, the fight was on," he told The Washington Post.

"They came with riot helmets, gas masks, shields, pepper spray, fireworks, climbing gear -- climbing gear! -- explosives, metal pipes, baseball bats," he said.

"I have never seen anything like it in 30 years of events in Washington."

Sund, who resigned over the stunning failure to defend the US legislature, said that two days earlier he had urged the mobilization of the National Guard to protect the white-domed Capitol building.

But he was told by the sergeant-at-arms of the House, Paul Irving, that the appearance of uniformed troops on the steps of the building would look bad.

On the day of the attack, Sund said the Pentagon was reluctant to deploy the National Guard.

A half-hour after the protesters arrived, he asked for reinforcements. But he was again told that it wouldn't look good.

The National Guard troops were finally mobilized but only arrived after the fighting had died down and Washington police had secured the building.

"This is how election results are disputed in a banana republic -- not our democratic republic," said former president George W. Bush.