The investigation by experts and police also showed that the tyres and tank of the bus “remained complete”, official state news agency Xinhua said.

A Communist Party news site said the suspect in a deadly bus fire killed himself in the blaze.

Party-run site Xianmen Net cited the local government’s news office on Saturday in saying the arson suspect died in the fire.

The report said police identified Chen Shuizong as the suspect after an on-site investigation, interviews and examination of evidence, including DNA. It says Chen was a local resident born in 1954.

Xianmen Net said police found a suicide note in his home and that Chen was unhappy and set the fire to vent his anger.

Xinhua reported that bus station staff were making “strict safety checks on passenger’s luggage” on Saturday.

In 2009, a bus in China’s southwestern city of Chengdu was set ablaze by an unemployed man with petrol, killing 28 people and injuring more than 70.

There have been previous reports of attacks on public transport in China, by people aiming to air personal grievances or settle scores with authorities.

Xinhua said there were 90 passengers on the Xiamen bus when it caught fire, five less than the vehicle’s capacity.

Thirty-four people were hospitalised following the blaze on the BRT (Bus Rapid Transit) vehicle, China’s deadliest transport accident in recent years.

Witnesses said the bus was destroyed within 10 minutes by the fire, and some heard a series of explosions.

Jiang Xiatong, who was sitting near the back window of the bus, told the state-run Global Times newspaper that she smelt a “peculiar odour” before the vehicle caught fire.

“While I was climbing, I felt my legs being pressed by someone, and then I felt a hot wave burn my legs,” she told the newspaper.

Another survivor told domestic media that passengers were asking “Who brought petrol on the bus?” moments before it caught fire.

The bus operated on a nine metre elevated road, in what was believed to be China’s first overhead rapid transport system when it was launched in 2008.

The network of three lines covers 67km, and carries 265,000 people a day, with buses often crowded during rush hour.

A total of 15 students were on board the bus, and seven of them are receiving medical treatment in hospital, Xinhua said.

Eight students remain missing, according to the Xiamen Municipal Education Bureau.

Xinhua also said that two candidates for the gaokao, China’s national university entry examination, were among those being treated at hospital. The two-day exam began on Friday.

“It was rush hour, the train was full and it was a total mess after the explosion,” a student surnamed Lu told the local Fujian web portal fjsen.com.

He also said his hair caught fire, but he escaped the blaze through the bus window.

Scores of netizens took to the internet to raise concerns immediately after the incident.

The Xiamen fire comes after a crash involving two high-tech bullet trains in the eastern province of Zhejiang in 2011 sparked public debate that officials were overlooking safety in their rush to develop the country’s vast transport network. More than 40 people died in that accident.

Xinhua said the launching of a criminal investigation casts doubt on whether “technical failure” was the cause of the tragedy.

Agence France-Presse and Associated Press