A burnt bus is seen at the scene of fire in Xinyang city, Central China's Henan province July 22. [Photo/Asianewsphoto]

ZHENGZHOU - Forty-one people died and six others were injured after an overloaded bus caught fire in Xinyang city, Central Henan Province, early Friday morning, the deadliest bus incident in years.

A total of 47 people were on board when the 35-seat bus caught fire at 4 am on the Beijing-Zhuhai Expressway. The cause of the blaze is still being investigated, said Zhang Guohui, head of the Henan Provincial Work Safety Administration.

Among the six injured, one person was in critical condition in Zhumadian No 159 hospital in Zhumadian city, while the other five, including the bus driver, were being treated in a hospital in Xinyang, according to Xinyang municipal police.

The double-decker sleeper bus was on its way from the city of Weihai in eastern Shandong province to central Hunan's provincial capital Changsha.

The body remains were burned beyond recognition and the deceased will have to be identified by DNA testing, according to police.

Ding Qingfa, who was slightly injured in the fire, got on the bus with five other people in Heze City, 500 km southwest of Weihai.

"I was sleeping but woke up by a sudden 'bang,' and I saw a big fire ball falling down, so I ran," Ding said.

He and his friends were sleeping in the aisle because the bus was already full when they boarded.

"People were screaming inside the bus, and the entire bus was on fire with black smoke spiraling," he said.

Ding said he asked the driver who had also fled the bus whether there was fire extinguisher, but the driver replied that it didn't matter - the fire was too big.

The driver is being questioned in hospital by police.

An investigation team from the State Administration of Work Safety has arrived at the site from Beijing to look into the incident.