San Francisco, California - The attacker who drove his car into the Chinese consulate in San Francisco before being shot and killed by police was armed with a knife and crossbow, the SFPD revealed.

San Francisco police on Thursday released footage of last week's attack showing the driver brandishing a knife after ramming his vehicle into the consulate's visa section, in the first official account of the incident.

Police bodycam footage shows an officer entering the consulate after 31-year-old Zhanyuan Yang had crashed into the building.

Police said consulate security had used pepper spray on the assailant.

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The video footage shows Sergeant Troy Carrasco telling Yang to get on the ground, who instead proceeds to slash at the officer with a knife.

Carrasco then appears to step back and shoot at Yang, before shouting at the security guards: "You should have told me he had a knife!"

Yang was taken to hospital where he died from his wounds.

San Francisco acting commander Mark Im said investigators found a "folding knife with a 3.5-inch blade, two 40-caliber fire cartridge casings, and one loaded center point crossbow with arrows" at the scene.

"Why he showed up there, what he was doing, that's still under investigation and there's nothing that we have at this point that I can release," Police Chief Bill Scott said.

The US has promised to cooperate with China and condemned violence against diplomatic missions after the attack.

San Francisco is home to a large number of ethnic Chinese residents, many of them critical of Beijing.

The Cuban embassy in Washington has been attacked twice in recent years, most recently by a person who last month threw two Molotov cocktails.