CHENGDU, June 8 (Xinhua) -- An investigation into a fatal bus blaze that killed 27 people and injured 74 others in southwest China shows someone had brought gasoline aboard the vehicle, an official said late Sunday, suggesting the inflammable material is to blame for the fire.

    Many people, including the bus driver, passengers, rescuers and other witnesses, told the investigators that they had sensed a smell of gasoline before the fire, He Jiansheng, of the investigation team, told reporters.

    Traces from the burnt bus were also found to contain substances of gasoline, He said.

    In addition, the bus did not use gasoline as fuel, but diesel oil instead, he said.

    "Therefore, we believe someone had brought gasoline aboard the bus," he said. "The combustion (of the gasoline) might have been triggered by a human error or by someone deliberately."

    But he said explosion can be ruled out as the cause of the bus fire, because no fragments of explosives have been found and no signs indicated an explosion had happened.

    The accident occurred in the morning rush hour Friday, when the No. 9 bus was on its way from Tianhui Township to downtown Chengdu, capital of Sichuan Province, and caught fire under the Chuanshan Viaduct. Altogether 25 were killed and 76 others were injured Friday.

    Two injured died in hospital Sunday, bringing the death toll to27.

    The two, who both suffered serious burns, included Yi Zunshun, a 69-year-old man, from Tianhui Township, who died in the General Hospital of the Chengdu Military Area Command at around 9:20 a.m., said Yang Wei, director of the Chengdu City Health Bureau, at a news briefing Sunday.

    The other was a 17-year-old boy named Liu Qi, who died around 5:15 a.m. in the Chengdu No. 2 People's Hospital, said the official.

    Eighteen injured people were still in critical condition, said Yang, adding doctors were trying their best to save their lives.

    Fifty-four others were in stable condition. Two have been discharged from hospital.