The chief of the US Capitol Police says the violent mob that stormed the building wielded metal pipes, chemical irritants and other weapons against law enforcement.
Steven Sund issued a statement saying the rioting protesters “actively attacked” police officers and “were determined to enter into the Capitol Building by causing great damage”.
A Capitol Police officer shot and killed one person, who Mr Sund identified as Ashli Babbitt.
Mr Sund did not identify the officer but said they would be placed on administrative leave pending an investigation.
Mr Sund defended his agency’s response from criticism that officers did not stop the incursion.
He says his agency “had a robust plan” for what he anticipated would be peaceful protests, but what occurred Wednesday was “criminal riotous behaviour”.
He said more than 50 Capitol and Washington police officers were injured and several Capitol Police officers were taken to hospital with serious injuries.
District of Columbia police later identified the three people who had medical emergencies and died during the storming of the Capitol.
They were 55-year-old Kevin Greeson, of Athens, Alabama; Rosanne Boyland, 34, of Kennesaw, Georgia; and 50-year-old Benjamin Phillips, of Ringtown, Pennsylvania.
Police chief Robert Contee would not go into detail about the exact causes of their deaths and would not say if any of the three was actively involved in breaching the Capitol building on Wednesday.
He said that all three “were on the grounds of the Capitol when they experienced their medical emergencies”.
Mr Greeson’s family said he had a heart attack. They described him as a supporter of Mr Trump but denied that he condoned violence.
Mr Phillips was the founder of a pro-Trump social media site called and had coordinated transport for several dozen people from Pennsylvania to Washington.
The Philadelphia Inquirer reported that he drove there in a van along with Trump-related memorabilia he had produced.
He was a web developer and founder of Trumparoo, a social media site for supporters of Mr Trump. His profile on the site said he was organising a bus from the Bloomsburg area to go to the rally and expressed anger at Democratic officials and moderate Republicans.
The Inquirer reported that members of his group say they last saw Mr Phillips at around 10.30am on Wednesday, and that he did not show up to meet them for a 6pm departure. They learned from police that he had died and had a sombre ride back to Pennsylvania.