Thirty-two passengers were injured after a bus caught fire on Saturday afternoon in downtown Hangzhou, capital of east China's Zhejiang Province.

The fire broke out at around 5 p.m. Saturday when the bus with about 80 people aboard was on the Qingchun Road in the downtown of Hangzhou.

Fifteen of the injured were in critical condition, said Yang Jianhua, spokesman for the Hangzhou Health Bureau.

As of 10 p.m.,one of the 30 hospitalized passengers was discharged from the No.2 Hospital affiliated to Zhejiang University after receiving treatment, said Yang, also deputy head of the bureau.

No death case has been reported, although doctors managed to help one injured person regain heart beating and breathing after their sudden stop.

Police are investigating the cause of the fire.

"So far, police have not found any clue to show the accident was related to terrorism," a source with the Hangzhou Public Security Bureau told Xinhua.

Smoke emerged in the carriage when the No.7 line bus went around at a road cross and then the bus stopped, said Zhou Dabo, a witness who was on the No. 27 line bus some 30 meters away from the No.7 line bus.

Drivers of some nearby private cars took out their extinguishers to join the efforts to put out the bus fire.

"Passengers rushed out after the bus's front door opened. Some smashed window glass and fled from the bus. Many people had smoke dust on their faces and some looked seriously injured," said another witness surnamed Xie.

"I was in the bus when I heard many people arguing in the back of the bus and then a fire broke out," said an injured person who is receiving treatment at the Hangzhou No.1 People's Hospital.

The blaze started in the middle of the bus and the clothes of the most seriously injured passengers were all burnt up and their hands were bleeding, said Wang Lei, a local subway company clerk who joined the rescue operation.

The fire had been put out at 5:50 p.m. Saturday. Traffic has resumed in the area.

The Hangzhou government has urged the strengthening of patrolling at important venues and the management of explosive and combustible goods to prevent emergencies.

In a separate bus accident, six people died and 36 others were injured after a bus overturned due to a tyre burst in southwest China's Chongqing Municipality on Saturday evening.