Capitol Police officer Brian Sicknick was injured whereas confronting protesters, the power stated in assertion.
He collapsed when he returned to his divisional workplace and was taken to hospital, the place he died from his accidents, they added.
It brings the loss of life toll from the riot to 5.
Wednesday’s breach of the legislative constructing got here as lawmakers had been certifying the victory of President-elect Joe Biden.
President Donald Trump condemns Capitol riot and concedes election to Joe Biden
Metropolitan murder officers will examine the loss of life of Mr Sicknick, who joined the Capitol Police in 2008, together with the Capitol power and its federal companions.
Mr Trump, who initially praised his supporters, later condemned the violence, saying the rioters had defiled the seat of American democracy and have to be held accountable.
Kayleigh McEnany: Administration discovered siege ‘appalling’
After a rally the place Mr Trump exhorted his supporters to “battle” to overturn the November 3 election he misplaced, tons of of them stormed the Capitol on Wednesday.
They compelled senators and members of the Home of Representatives to evacuate as they smashed home windows and looted.
As Democratic leaders demanded he’s ousted, Mr Trump got here nearer to a proper concession.
He acknowledging in a video launched on Thursday night {that a} “new administration” can be sworn in on January 20 and vowed to make sure a “clean transition” of energy.
