A motorist was shot dead on Friday after he tried to run down two U.S. Capitol policemen on Friday.
The action triggered a lockdown of the abutting streets.
Capitol police said the suspect was initially arrested. He later died in the hospital.
Both officers are injured and have been transported to the hospital,” the USCP statement said.
Dozens of police cars, marked and unmarked, raced toward the Capitol building.
All roads leading to the complex were blocked by police or police officers.
A helicopter was seen hovering overhead and observers were ordered to leave the area.
Videos from the scene showed what looked like two policemen on stretchers being loaded into ambulances.
Authorities have begun only in the past couple of weeks to remove the outer ring of high, razor-wire-topped fencing erected around the sprawling Capitol complex.
This followed the attack on Jan. 6 by thousands of supporters of then-President Donald Trump.