The incident took place at the northwestern entrance of the US Capitol, where senators and staff normally enter the building. The outermost fence perimeter police set up in the wake of the January 6 attack was removed last week, opening the area to public traffic.
Footage from outside Congress showed two stretchers and a large gathering of law enforcement officers.
Congress is currently on recess and politicians are out of town. President Joe Biden is currently at Camp David receiving information about the incident, the White House said.
The president is now at Camp David and @presssec says as always he has a national security team with him that can provide information about events like the security situation unfolding at the US Capitol.
Friday’s incident is the first attempted security breach since supporters of former US president Donald Trump violently stormed the Capitol in hopes of preventing Congress from certifying Joe Biden’s 2020 election victory.
More than 140 Capitol Police officers suffered injuries during the attack. Five people died during or shortly after.