At least four people, including a police officer, were killed near the British Houses of Parliament in London during a wild attack that’s being treated “as a terrorist incident,” according to reports.

The attacker also died after he was shot by police, Scotland Yard officials said. At least 20 others were injured.

One woman died and at least 10 others were wounded when a gray Hyundai i40 mowed down several people on the Westminster Bridge before crashing into the gates outside Parliament, according to The Telegraph.

The attacker then reportedly ran through the gates and stabbed a policeman with an “8-inch” knife before being shot, The Independent reported. The policeman died at the scene from his wounds, a Foreign Office minister who gave mouth-to-mouth resuscitation to the officer told the BBC.

“He (the assailant) ran in through the open gates … He set about one of the policemen with what looked like a stick,” said journalist Quentin Letts, who watched the carnage unfold from his office in the Parliament building.

“The policeman fell over on the ground and it was quite horrible to watch and then having done that, he disengaged and ran toward the House of Commons entrance used by MPs (members of Parliament) and got about 20 yards or so when two plain-clothed guys with guns shot him.”

Disturbing photos show several injured people lying on Westminster Bridge as they get assistance from bystanders. One woman believed to have been on the bridge during the attack was found in the River Thames and pulled out alive.

“There were people across the bridge. There were some with minor injuries, some catastrophic,” a doctor at St. Thomas’ Hospital told reporters. “Some had injuries they could walk away from or who have life-changing injuries. There were maybe a dozen [injured].”

Steve Voake, 55, told NBC News he heard screaming as he was walking over the bridge.

“I thought it was a road accident,” he explained. “There was lots of panic and confusion. Then I saw a shoe on the ground. I saw one body on one side of the road and one body face down in the water with blood all around it.”

Two people reportedly were seen lying outside Westminster Hall. The House of Commons has been suspended, and Prime Minister Theresa May was rushed away in a car, according to reports.

“At the moment, the very clear advice from the police and the director of security in the house is that we should remain under suspension, and that the chamber should remain in lockdown until we’ve received advice that it is safe to go back to normal procedures,” Lidington said.

Scotland Yard said the attack was being treated “as a terrorist incident until we know otherwise,” according to The Telegraph.

President Trump has been updated on the situation. White House press secretary Sean Spicer said the US will continue to monitor the incident.

“I was just getting an update on London,” he told reporters Wednesday morning. “Some big news having to do with London just happened.”

Exactly one year ago, suicide bombers in Brussels staged coordinated attacks that left 32 people dead.