One officer received severe injuries and was in the intensive care unit, according to doctors.

"When four of them were carried into the emergency room, their bodies were soaked with blood and their faces were pale," a Changzheng Hospital witness, surnamed Jia, told Xinhua.

Policeman Fang Fuxin, 47, died before reaching the hospital and Zhang Jianping, 48, died two hours after admittance. Both succumbed to heavy bleeding in the lower right lung, according to doctors. The names of the three other dead officers have not been released.

The other two officers at the Changzheng Hospital, both in their 30s, were last night in a stable condition and recovering from head and chest wounds.

A police cordon was set up around the building after the attack, and the broken glass bottle which the suspect used to set the fire was still at the scene in the early afternoon.

Services at the Zhabei bureau, including issuing ID cards for residents, were suspended yesterday.

According to the Zhabei District Public Security Bureau, the police officers at the attack scene - and the security officer - were not authorized to carry batons or guns.