THAI police arrested the driver of a bus carrying young students and teachers that caught fire and killed 23 in suburban Bangkok.

Saman Chanput has been charged with reckless driving causing deaths and injuries, failing to stop to help others and failing to report the accident.

The arrest comes as families arrived in the capital today to help identify their loved ones.

The bus carrying six teachers and 39 students in elementary and junior high school was travelling from Uthai Thani province, about 186 miles north of Bangkok, for a school trip in Ayutthaya and Nonthaburi provinces on Tuesday. 

The fire started while the bus was on a highway north of the capital and spread so quickly that many were unable to escape.

Trairong Phiwpan, head of the police forensic department, said 23 bodies were recovered from the burnt out wreckage of the bus. 

Mr Saman told investigators he was driving normally until the bus lost balance at its front right tyre, hit another car and scraped a concrete highway barrier, causing the sparks that ignited the blaze, Chayanont Meesati, deputy regional police chief, told reporters.

The driver said he ran to grab a fire extinguisher from another bus that was travelling for the same trip but he could not put out the fire, and ran away because he panicked, Mr Chayanont said.