US Capitol Police detain rioters outside of the House chamber. (Photo by Getty Images)

Four Americans have been killed as supporters of President Donald Trump stormed the US Capitol on Wednesday to stop Congress from certifying President-elect Joe Biden’s victory in the November election.

A young woman was shot and killed by the police inside the building while three others died because of medical emergencies. 14 police officers were injured - two of whom remain hospitalized. 52 Trump supports were also arrested.

Video shows moment woman killed by police in US Capitol amid riot pic.twitter.com/YcDBbDAjYd

— PTV UK (@Presstvuk) January 7, 2021

In a late night news conference, Metropolitan Police Department Chief Robert J. Contee declined to identify the woman a Capitol Police officer shot and killed, saying next of kin notification was still pending.

Contee also said 47 of the 52 arrests were related to violations of Mayor Muriel Bowser’s 6 p.m. curfew, with 26 of those involving people arrested on US Capitol grounds.

The Capitol Police are now facing questions about why they did not do more to secure the Capitol and let many of the rioters later exit the building without arrests.

Washington D.C. mayor Muriel Bowser’s Bowser said police intend to ask the public for help in identifying rioters, many of whom posed for photos inside the Capitol.

We will be on the lookout, she said. Some of them, we think ... have to be held accountable for the carnage.

The FBI also asked the public to submit tips, such as images, videos and other information to help agents identify people were actively instigating violence in the pro-Trump rally.