Capitol Police said someone "rammed a vehicle into two USCP officers" and a suspect was taken into custody, but had since died.
In a tweet Friday, Senate Minority Leader Mitch McConnell said, "Praying for the United States Capitol Police officers who were attacked at the Capitol". He exited the vehicle and began "lunging" toward police with a knife visible in his hand, at which point officers fired their weapons, killing the suspect. She did not provide additional details, saying next of kin have yet to be notified.
"Today, America's heart has been broken by the tragic and heroic death of one of our Capitol Police heroes: Officer William Evans". The suspect also died at a hospital.
He told reporters the suspect did not appear to have been on police radar.
Video and images from the scene showed a dark coloured sedan crashed against a vehicle barrier and a police K-9 inspecting the vehicle. Footage of what appears to be two people on stretchers were posted by Fox News' Jacqui Heinrich. "If you are outside, seek cover".
The locality around the US Capitol and congressional office buildings were immediately put on a lockdown as dozens of marked and unmarked police cars raced toward America's legislative seat.
President Joe Biden left Washington earlier in the day for Camp David, the presidential retreat in Maryland.
Both of the Capitol Police officers received emergency medical attention. MPD provided no other details. "This has been an extremely hard time for U.S. Capitol Police after the events of January 6 and now the events that have occurred here today".
In recent weeks, some security has been loosened, with the number of armed National Guard troops at the Capitol reduced and a security fence that created a broad perimeter around the Capitol complex removed.
Security officials, including the Capitol Police and National Guard, were faulted for reacting slowly to the crowds who stormed the Capitol on January 6. The outer ring of fencing was taken down just this week, although an inner ring of fencing remains around the U.S. Capitol building.
But the danger on Friday was limited as Congress was in recess for the Easter holiday and relatively few people were in the building. "Whether the attack was at law enforcement, or whoever, we have a responsibility to get to the bottom of it and we'll do that", Contee said.