The cause of the blaze in Chengdu, the capital of Sichuan province, remained under investigation, according to a report on a Web site run by the provincial government's propaganda department.
Photos posted on blogs and Internet forums showed the bus consumed by flames. One badly burned woman was shown lying on the road with a man standing over her, his clothes burned off.
The government report said 76 people were being treated at a pair of hospitals. More than two dozen of those injured were considered serious, it said.
[...] State broadcaster CCTV cited witnesses as saying the sealed, air-conditioned bus caught fire without an explosion, and then burned rapidly. Like many vehicles in Chengdu, the bus ran on natural gas rather than gasoline.
See also ESWN for video and images of the fire (warning: some images are very graphic).