The Office of Police Forensic Science has determined that the bus fire that killed 20 children and three teachers on Tuesday resulted from a gas leak, from on of 5 illegally installed cylinders on the bus.

Yesterday, Pol Lt Gen Trairong Phiewphan, the commander of the Office of Police Forensic Science (OPFS), announced that an examination of the bus wreckage revealed that the gas leak and subsequent fire was the result of an unregistered CNG tank that had not been inspected by regulators.

An inspection of wreckage revealed that 11 tanks containing compressed natural gas (CNG) had been installed on the bus. Six of the tanks were registered, while the remaining 5 tanks were not.

The inspection also revealed the gas leak originated from one of the unregistered tanks, but it has not yet been determined what caused the sparks that ignited the compressed CNG gas, nor why the gas was leaking.

He added that the bus’s front-wheel shaft was broken, but there were no signs of scraping from against the road surface.

Additional cylinders that had been illegally installed on the buses – Post Media Image

Meanwhile, the Department of Land and Transport has suspended the licence of the bus owner after he was caught trying to hide unregistered gas cylinders installed on 5 other buses in the same fleet after the company failed to send the buses for inspection on Thursday.

Department of Land and Transport officials tracked down the buses via GPS and found then at a garage in Nakhon Ratchasima, where they were removing illegally installed CNG gas cylinders, Mr. Jirut Wisanjit, the director-general of the department reported.

He said this indicates the bus owners intention to conceal the wrongdoing of the illegal modification of the vehicles.

The five buses were part of a six-bus fleet which included the bus that caught fire and killed 20 students and three teachers from Uthai Thani during a field trip on Tuesday.

According to Mr. Jirut, the bus involved in Tuesday’s tragedy had been in service for more than 50 years and had been modified multiple times, and had been refitted to use CNG gas but the installation was not up to standard nor certified.

He said the licence of the bus driver, identified as Mr. Samarn Chanphut, 48, who surrendered to police on Tuesday night, has also been suspended. He is presently facing 4 criminal charges and will also lose his licence if found responsible.