A man armed with a knife stormed a police station in Shanghai on Tuesday, attacking officers and killing at least five, authorities said.
The 28-year-old man, surnamed Yang, set a fire outside a gate of the building, then rushed inside and began stabbing officers, the Shanghai Public Security Bureau said in a news release.
Five officers died after being taken to a hospital, while four other police officers and a security guard were hurt, the statement said. Some had chest wounds and others had bloodied faces, the official Xinhua News Agency reported, citing a witness surnamed Yi.
Yang, who was from Beijing and unemployed, said he was seeking revenge after officers at the station in Shanghai's Zhabei district investigated him last year for allegedly stealing bicycles, police said.
Yang was taken into custody at the station.
It was not clear how Yang managed to attack so many police officers and why he was not detained after setting a fire outside the building. Chinese police are permitted to carry guns.
A woman at the Zhabei district station referred questions to the Shanghai Public Security Bureau. Phones were not answered in the bureau's propaganda department.
Violent crime is rare in China, where private gun ownership is virtually banned, although there have been scattered cases of revenge attacks.