WASHINGTON — A Capitol Police officer was killed Friday after a man rammed a car into two officers at a barricade outside the U.S. Capitol and then emerged wielding a knife, marking the second line-of-duty death this year for a department still recovering from the Jan. 6 insurrection. 

Video shows 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. The driver stabbed one of the officers, Pittman said. Authorities shot the suspect, who died at a hospital.

"I just ask that the public continue to keep U.S. Capitol Police and their families in your prayers," Pittman said. "This has been an extremely difficult time for U.S. Capitol Police after the events of Jan. 6 and now the events that have occurred here today."

.@ABC NEWS SPECIAL REPORT: Officers injured, "suspect is in custody" amid incident at U.S. Capitol, Capitol Police says.

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Pittman did not identify the slain officer or suspect. Authorities said that there wasn't an ongoing threat and that the attack did not appear to be related to terrorism. There was also no immediate connection apparent between Friday's crash and the Jan. 6 riot.

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 Jan. 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.

BREAKING – Multiple US Capitol police officers have been shot according to the radio. More police units rush to the complex.pic.twitter.com/t2hmyh0aYP

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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 officer who died Friday is the seventh Capitol Police member to die in the line of duty in the department's history. Two officers died by suicide following the Jan. 6 attack.

The security checkpoint is typically used by senators and staff on weekdays, but lawmakers are away on break. The attack occurred about 100 yards (91 meters) 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 U.S. 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 mobilizing near the area of the crash.

Video posted online showed a dark colored sedan 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 traveling with a member of the National Security Council Staff who was expected to brief him on the incident.