Washington — A U.S. Capitol Police officer was killed Friday after a car rammed a security barricade protecting the complex, locking down the building for two hours and reigniting tensions in a city still struggling to return to normalcy after the deadly Jan. 6 insurrection.

According to Capitol Police, a man drove his car into two officers and then crashed into the barricade. The blue sedan appeared to hit a barrier that can be raised while Capitol Police search a vehicle and verify its occupants’ identities. The driver exited the vehicle with a knife, “lunged” at one of the officers and was shot by police, officials said.

The suspect was taken into custody. He and the two seriously injured officers were transported to hospitals, where one officer and the suspect died, officials said.

“It is with a very, very heavy heart that I announce one of our officers has succumbed to his injuries,” said Yogananda Pittman, acting chief of the U.S. Capitol Police. “This has been an extremely difficult time for the U.S. Capitol Police.”

She later identified the officer as William “Billy” Evans, an 18-year veteran of the Capitol Police force who was a member of the division’s first responders unit.

House Speaker Nancy Pelosi (D-San Francisco) called Evans a “martyr for our democracy” and ordered flags at the Capitol to be flown at half-staff.

President Biden, who is spending the weekend at Camp David, sent condolences to Evans’ family.

“Jill and I were heartbroken to learn of the violent attack at a security checkpoint on the U.S. Capitol grounds, which killed Officer William Evans of the U.S. Capitol Police and left a fellow officer fighting for his life,” Biden said. “We know what a difficult time this has been for the Capitol, everyone who works there and those who protect it.”

Biden ordered flags to be flown at half-staff at the White House and all public buildings and grounds through Tuesday.

Police said later Friday that the second officer struck by the car, who was not identified, was in stable condition. One law enforcement source said the officer had broken bones.

Evans’ death is the second in the line of duty for the U.S. Capitol Police this year. Officer Brian Sicknick died from injuries sustained during the Jan. 6 insurrection; two other officers died by suicide in the weeks after that attack. Prior to this year, a total of four officers had died in the line of duty in the history of the force, according to the Capitol Police.

The incident does not appear to be related to terrorism, according to Robert Contee, acting chief of D.C. Metropolitan Police.

“We need to understand the motivation,” he said.

Pittman said Capitol Police did not have the suspect on file, and there were no early indications that the incident was related to a threat to any specific member of Congress.

A law enforcement official familiar with the case identified the suspect as Noah Green, 25, of Indiana. Investigators were digging into Green’s background in search of a motive.

“We haven’t found any manifestos,” a senior law enforcement official said. “We haven’t found anything like he hates cops or Congress.”

In the last month, Green lost his job and apartment in Indiana, the official said, and police were trying to determine where he had been living.

Green was a 2019 graduate of Christopher Newport University in Newport News, Va., with a degree in finance. He played on the university’s football team in the fall 2017 and fall 2018 seasons.

Two law enforcement officials told the Los Angeles Times that authorities were reviewing social media posts made by Green, including items related to the Nation of Islam. A Facebook page that appeared to belong to him had been taken down Friday night, according to multiple media reports.

At approximately 1:10 p.m. Friday, Capitol staff were instructed by Capitol Police to remain indoors and away from external windows due to an “external security threat.”

Video shot by reporters on the scene showed at least two dozen National Guardsmen running in a line toward the intersection as people trying to enter the Capitol were directed away. Other uniformed security forces were deployed around the area. Another video showed what appeared to be a National Park Service helicopter landing on the lawn on the East Front of the Capitol.

Tensions have been high in Washington since the Jan. 6 insurrection, when mobs of violent supporters of President Trump stormed the Capitol.

“It did bring back memories of Jan. 6,” Rep. Ro Khanna (D-Fremont) told.

The black fencing and enhanced security that enclosed the sprawling Capitol complex in the wake of that attack had started to come down in recent weeks. The security perimeter shrank, although the fencing is still up at the intersection on the north side of the complex where the incident took place.

Security recommendations have called for additional permanent fencing at the Capitol, but lawmakers of both parties have been hesitant to support this, worried about the optics of Congress walling itself off from the public. Friday’s incident is likely to reignite those conversations.

Sen. Dianne Feinstein (D-Calif.) called for a review of the Capitol’s security provisions.

“This is the second attack on the Capitol in just three months, and it has become clear the Capitol is increasingly seen as a target,” she said.

Rep. Tim Ryan (D-Ohio), who leads one of the subcommittees that oversees the Capitol Police, said the incident would spark closer scrutiny of the fences that have lined the complex for three months and calls to remove them.

“It’s a disturbance. It’s an eyesore. It sucks. Nobody wants that there,” Ryan said of the fence. “But the question is whether the environment is safe enough to be able to take it down and, in the meantime, maybe that fence can prevent some of these things from happening.”

In 2016, Capitol Police shot a man who tried to bring a fake Beretta into the Capitol Visitor Center.

Congress is on recess this week for the spring holidays, so the Capitol complex had far fewer people than normal. The vast majority of lawmakers were expected to be in their districts and not in the Capitol. On a recess day, the building is still populated by staff members, reporters and police officers.