At least four people have died during riots at the US Capitol on Wednesday, police have said.

Three people died from medical emergencies, according to law enforcement.

A woman was also shot, named by local media as Ashli Babbitt.

“We will not know the cause of death – we believe some type of medical emergency,” Washington DC’s Metropolitan Police Department chief Robert Contee said on Tuesday night.

“The gunshot wound victim … she is the one transported from the scene to an area hospital.”

At least 52 people have been arrested, mostly for breaking curfew, according to the chief.

Police have said at least four people have died during the protests, which saw crowds storm the US Capitol building
Police have said at least four people have died during the protests, which saw crowds storm the US Capitol building

Washington DC Mayor Muriel Bowser set a 12-hour curfew, from 6pm Wednesday into Thursday morning.

Officers also recovered two pipe bombs, one at the headquarters for the Republican National Committee and another at the Democratic National Committee, Chief Contee said.

Also, a cooler filled with a long gun and molotov cocktails were also discovered on the grounds.

Police say four people have died during the riots

Pro Trump supporters breached the halls of Congress on Wednesday, forcing staff and lawmakers to barricade themselves in offices and take cover under chairs in the House.

At least 13 people were arrested during the riots and Washington Police said five guns, including handguns and long guns have been seized.

Reporters were also told some officers are being treated for injuries.

The US Capitol was later secured at around 11pm GMT, following the dramatic scenes.

U.S. Capitol police officers point their guns at a door that was vandalized in the House Chamber
U.S. Capitol police officers point their guns at a door that was vandalized in the House Chamber

It's also being reported Ashli Babbitt, who has been named as the woman who was gunned down, was shot.

She was pronounced dead at a nearby hospital.

Metropolitan Police Department's are investigating the incident.

Three other people died from medical emergencies, added the police.

"One adult female and two adult males appear to have suffered from separate medical emergencies, which resulted in their deaths. Any loss of life in the District is tragic and our thoughts are with anyone impacted by their loss," Contee said at a news conference Wednesday night.

In a bit to split up the crowd, smoke grenades were used. The building has been left with broken windows and hundreds of officers inside.

Lawmakers returned to the Capitol after the building was secured, and made it clear they intended to resume business - confirming Biden's win over Trump by counting the votes in the Electoral College.

"Today, a shameful assault was made on our democracy. It was anointed at the highest level of government. It cannot, however, deter us from our responsibility to validate the election of Joe Biden," House Speaker Nancy Pelosi wrote.

"To that end, in consultation with Leader Hoyer and Whip Clyburn and after calls to the Pentagon, the Justice Department and the Vice President, we have decided we should proceed tonight at the Capitol once it is cleared for use. Leader Hoyer will be sending out more guidance later today."