As his supporters storm into the US Capitol in quickly-escalating protests, Donald Trump has broken his silence and tweeted for demonstrators to "support Capitol Police and Law Enforcement".

"They are truly on the side of our country," he wrote. "Stay peaceful!"

US media report that tear gas has now been used inside the Capitol building as a growing number of demonstrators enter the building.

DC Mayor Muriel Bowser has ordered a citywide curfew beginning at 1800 EST.