Beijing - At least 35 people were killed and 11 injured when a bus crashed on a highway in central China Sunday and burst into flames, state media reported.
Huge clouds of thick black smoke billowed from the vehicle after the bus slammed into a roadside concrete barrier in Hunan province, video footage showed. One person was seen being dragged to safety.
Some passengers limped out of the bus covered in blood, the state news agency Xinhua reported.
It quoted a survivor surnamed Huang as saying the driver told he could not open the bus door, before escaping from the window beside his seat.
Huang saved himself by smashing another window with a fire extinguisher.
Two children were among those killed, while four of the 11 people taken to hospital were seriously injured, Xinhua said, adding that the bus driver had been detained.
Images recorded after the fire in Yizhang county was extinguished showed the charred bus totally destroyed and sitting atop a pile of ash.
A total of 55 people were on the vehicle, Xinhua cited local officials as saying.
Local officials believe that an oil leak caused by the crash may have sparked the huge blaze, it said.
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Traffic accidents are common in China, with more than 250,000 people dying each year on the country's roads, according to the World Health Organization.
Public Security Minister Guo Shengkun has ordered intensive efforts to save the injured, establish the cause of the accident and take measures to prevent a recurrence, Xinhua said.
It said a team headed by Vice Public Security Minister Huang Ming was heading to the scene.
Long-distance buses are a popular cheap mode of travel between cities and competition between transport firms can be fierce.
China has seen repeated bus fires in recent years which have caused multiple fatalities.
A total of 38 people were killed in 2014 when a van carrying flammable liquid hit a bus on a highway in Hunan province.
In 2010 a shuttle bus carrying steel factory workers in eastern China burst into flames, killing 24 passengers.
Several such incidents were deliberate arson attacks, according to officials.
An arsonist who injured more than 30 people by setting fire to a bus in the city of Hangzhou was executed last year.
In 2013 a suicidal man started a fire on a vehicle in Xiamen that killed 47 people including himself.
There were no indications that the fire on Sunday was deliberate. Xinhua said rescuers were searching the charred frame for clues.