"We mourn the victims, and express our sympathy to their families and those injured," foreign affairs spokeswoman Mao Ning told a regular press conference.

American officials have identified the attacker as Shamsud-Din Jabbar, a 42-year-old US army veteran from the neighbouring state of Texas.

Mao told journalists: "We are shocked by this violent attack... China always opposes any violent and terrorist acts targeting civilians."

She added that Beijing had not received any reports of Chinese casualties from the country's embassy in the United States.