A US CAPITOL police officer has died of injuries sustained during clashes with a mob of Donald Trump’s supporters who overran a session of Congress, police said late last night.

It is the first law enforcement death stemming from the violence at the Capitol on Wednesday which saw flag-waving crowds break into the legislature.

Four protesters died, including a woman who was shot by police. Three other deaths were reported on the Capitol grounds, but the circumstances remained unclear.

Washington police chief Robert Contee said on Wednesday that the three other people who died “appeared to have suffered medical emergencies which resulted in their deaths”.

Officer Brian Sicknick, a 12-year veteran of the force, was “responding to the riots on Wednesday, January 6, 2021, at the US Capitol and was injured while physically engaging with protesters,” Capitol Police said in a statement.

“He returned to his division office and collapsed. He was taken to a local hospital where he succumbed to his injuries” last night, it said.

On Wednesday, the US Capitol went into lockdown, with politicians inside, as a protest by pro-Trump supporters became a mob which broke into the building and occupied offices. 

The violence broke out as the US Senate and House were in the process of approving the Electoral College votes of all 50 states and rubber-stamping November’s election result.

Biden’s win has since been officially certified after politicians resumed their proceedings following the disruption.