The accident happened at about 3am on a major expressway near Shaoyang . The van rammed the double-decker coach carrying 53 passengers and two drivers, setting off explosions and a fire that destroyed three other vehicles. The blaze took five hours to extinguish.

The coach was travelling to Guizhou along the Hukun Expressway that connects Shanghai with Kunming , capital of Yunnan . About half the passengers boarded the bus in Xiamen , Fujian .

The van's driver and a passenger died at the scene, Xinhua said.

Shi Shiping, a villager living near the accident scene, told Xinhua that he "heard a big bang" at the time of the accident. A worker at a local hospital said that all the clothes of the injured were severely burned, Beijing News reported.

The younger brother of one of the passengers, who identified himself only by his surname Tang, told the he was notified of the accident by local police almost 12 hours after the accident. The fate of his sister is unknown.

Tang said his sister worked in Xiamen, but was travelling to be with her daughter who was applying for an identity card in their hometown in Yunnan.

"Our parents back home are very worried," said Tang, who travelled to the accident scene. "We may take legal action against the bus operator as passenger buses are banned on highways in the middle of the night."

Mainland media reported that the operator was one of the four companies cited by the Putian city government in Fujian on Friday for running coaches on highways between 2am and 5am.

Calls to the operator for comment went answered.

Senior officials from the State Administration of Work Safety, the Ministry of Public Security and the Ministry of Transport headed to the site for investigation, Xinhua reported.