Joe Biden has said he is heartbroken after a police officer was killed when a man rammed a car into two officers at a barricade outside the US Capitol in Washington DC and then emerged wielding a knife.
Video showed the driver of the crashed car emerging with a knife in his hand and starting to run at the pair of officers, Capitol Police Acting Chief Yogananda Pittman told reporters.
Authorities shot the suspect, who died at a hospital.
Mr Biden said in a statement he and wife Jill Biden sent their condolences to the family of the officer who was killed, who police identified as William “Billy” Evans.
“I just ask that the public continue to keep US Capitol Police and their families in your prayers,” Ms Pittman said.
“This has been an extremely difficult time for US Capitol Police after the events of January 6 and now the events that have occurred here today.”
Two law enforcement officials told The Associated Press that investigators initially believed the suspect stabbed one of the officers, but it was later unclear whether the knife actually made contact, in part because the vehicle struck the officers with such force.
The officials were not authorised to publicly discuss the investigation and spoke on condition of anonymity.
Authorities said that there was not an ongoing threat and that the attack did not appear to be related to terrorism.
Law enforcement officials later identified the dead suspect as 25-year-old Noah Green.
Investigators were digging into the suspect’s background and examining whether he had any mental health history as they tried to discern a motive.
They were working to obtain warrants to access his online accounts.
There was also no immediate connection apparent between Friday’s crash and the January 6 riot.
Green described himself as a follower of the Nation of Islam and its founder, Louis Farrakhan, and spoke of going through a difficult time where he leaned on his faith, according to recent messages posted online that have since been taken down.
The messages were captured by the group SITE, which tracks online activity.
“To be honest these past few years have been tough, and these past few months have been tougher,” he wrote.
“I have been tried with some of the biggest, unimaginable tests in my life. I am currently now unemployed after I left my job partly due to afflictions, but ultimately, in search of a spiritual journey.”
The crash and shooting happened at a security checkpoint near the Capitol as Congress is on recess.
It comes as the Washington region remains on edge nearly three months after a mob of armed insurrectionists loyal to former president Donald Trump stormed the Capitol as Congress was voting to certify Joe Biden’s presidential win.
Five people died in the January 6 riot, including Capitol Police officer Brian Sicknick, who was among a badly outnumbered force trying to fight off insurrectionists seeking to overturn the election.
Authorities installed a tall perimeter fence around the Capitol and for months restricted traffic along the roads closest to the building, but they had begun pulling back some of the emergency measures in recent weeks.
Ms Pittman said the suspect did not appear to have been on the police’s radar. But the attack underscores that the building and campus — and the officers charged with protecting them — remain potential targets for violence.
The security checkpoint is typically used by senators and staff on weekdays, but lawmakers are away on break. The attack occurred about 100 yards from the entrance of the building on the Senate side of the Capitol.
Fencing that prevented vehicular traffic near that area was recently removed, but there was additional interior fencing between the checkpoint and the building.
The suspect had been taken to the hospital in critical condition. One of the officers who was injured was taken by police car to the hospital; the other was transported by emergency medical crews.
The US Capitol complex was placed on lockdown after the shooting, and staffers were told they could not enter or exit buildings. Video showed National Guard troops mobilising near the area of the crash.
Video posted online showed a dark coloured car crashed against a vehicle barrier and a police K-9 inspecting the vehicle. Law enforcement and paramedics could be seen caring for at least one unidentified individual.
President Biden had just departed the White House for Camp David when the attack occurred. As customary, he was travelling with a member of the National Security Council Staff who was expected to brief him on the incident.