US police said they shot dead a driver whose car crashed into the Chinese consulate in San Francisco on Monday.

Unverified footage on social media showed a vehicle inside the building with officers pointing their weapons at the driver's door, as people fled downstairs and into the open.

A spokesperson for the San Francisco Police Department said the vehicle had crashed into the visa office of the consulate in the middle of the afternoon, but officers were unable to say whether it had been a deliberate act.

"Officers entered, made contact with the suspect and an officer-involved shooting occurred," a spokesperson for San Francisco Police Department told reporters.

The spokesperson said officers, paramedics and medics had tried to save the suspect's life, but that the person was pronounced dead at the hospital some time later.

The spokesperson gave no details about the suspect's identity.

The local ABC7 News channel said its crews had seen a man covered in blood and apparently unresponsive being taken away from the scene.

"This is an open and active investigation and the San Francisco Police Department is currently working in coordination with investigators from the US State Department," the police spokesperson said.

A spokesman for the Chinese consulate in San Francisco said an "unknown person" had violently crashed into the building, posing a serious threat to the safety and lives of its staff members.

The spokesman said the consulate condemns the violent attack and reserves the right to take legal action, adding that it has lodged solemn representations with the US. (AFP/Xinhua)