POLICE are checking video footage from closed-circuit cameras on a Bangkok expressway in a bid to determine the cause of Sunday's horror van crash, which killed nine passengers.

The driver of the van, who had 16 passengers on board, looks set to face a raft of charges, including reckless driving causing death, police said on Monday.

The gas-fuelled van plunged off the expressway near the Rama VI exit and burst into flames.

The accident claimed nine lives. Two survivors are in a critical condition in Ramathibodi and Chulalongkorn Hospitals, while six more - all said to be seriously hurt - are being treated in several other hospitals.

'Initial evidence suggests no other vehicles were involved,' Police Lt Col Pada Akranithi said on Monday, in his capacity as an investigator at the National Police Office's Traffic Division.

Weerayut Pansombat, the 27-year-old son of the van driver, said he was told a female passenger shouted out during the trip that she smelled gas.

Driver faces serious charges