Sabotage can not be ruled out as the cause of a fatal bus blaze that killed 25 people and injured 76 others Friday in southwest China's Chengdu City, said an official in Chengdu on Saturday.

Hu Qinghan, director of the Chengdu Communications Commission, said that according to an initial investigation, self-combustion or a mechanical glitch cannot be concluded as the cause of the blaze.

The bus had run 268,000 kilometers as of the time of the accident since it was put into operation in 2005, less than the 500,000-km standard for scrapping.

The bus received a routine maintenance on May 25. It was filled with 137 liters of diesel on June 4 and investigators found the tank still contained 107 liters of the fuel after running 160 km in a day. No mechanical glitch was detected in the engine.

"The blaze was not fueled by diesel in the oil tank," said Hu.

He said that the bus driver failed to open the cab door after the accident. He got off and found the fire extinguisher, which he then used to break the window of the bus to help passengers out.

The driver, Luo Pei, 45, has been driving for 15 years, including eight years of buses. He has a safe driving record of five years.

Witnesses said Luo managed to rescue passengers.

The bus was equipped with firefighting facilities, and three safety hammers for breaking windows were found in the debris of the bus.

The accident occurred in the morning rush hour Friday, when the No.9 bus, with license plate Chuan A 49567, was on its way from Tianhui Township to downtown Chengdu, and caught fire under the Chuanshan Viaduct.

Chen Xiangjun, vice director with the municipal civil affairs bureau, said ten of the 25 people, ten men and 15 women, killed in the blaze have been identified after DNA tests.

Chen called upon family members of the victims to provide DNA samples for the identification of the remaining ten deaths.

So far, six of the 76 injured passengers on the bus are in critical condition, with 95 percent of their bodies seriously burnt.

Three slightly injured people have been discharged from hospital, he said.

Among the injured, 35 are male and 38 are female. The oldest one is 72years old, and the youngest is five.

"The bus had air conditioning and only the windows at the rearmost seats could be opened by hand," said 29-year-old Deng Huaqiong. She sat on the second row from the rear and jumped out after someone opened the back window. She suffered slight burns and was receiving treatment in hospital.

Passers-by smashed the windows from the outside, which helped save some of the passengers.

The deadly accident has prompted a number of Chinese cities to launch bus safety overhauls and enhanced public transportation management and supervision.

Xi'an, capital of Shaanxi Province, has inspected more than 4,000 buses for firefighting equipment.

Wuhan, capital of Hubei Province, began to check the circuit system in prevention of fire in summer.

Chongqing Municipality are examining its 6,500 buses on tanks, circuit, engines and other key functional parts, while asking passengers not to bring dangerous materials onboard.

Changchun, capital of Jilin Province, launched a bus fire firefighting drill Friday night.

Fuzhou, capital of Fujian Province, will equip 300 new buses with automatic fire extinguishers this year. About 1,500 of the city's 2,100 buses have been installed with the automatic firefighting facilities, costing more than 3 million yuan.

(Xinhua News Agency June 7, 2009)