BANGKOK, Oct 1, 2024 (BSS/AFP) - A devastating fire on a Thai school bus killed at least 23 people, police said Tuesday after rescuers pulled children's bodies from the charred wreckage of the vehicle.

The inferno engulfed the coach on a highway in a northern Bangkok suburb as it carried 38 children -- ranging from kindergarten age to young teenagers -- and six teachers on a school trip.

It is believed to be the deadliest road accident in a decade in Thailand, which has one of the world's worst traffic safety records with around 20,000 fatalities a year.

"We found 23 bodies inside the bus," Trairong Phiwpan, head of the police forensic science office, told reporters. 

The victims' bodies were so badly burned that Trairong said it was not yet possible to confirm how many were adults and how many children. 

DNA testing would be needed to identify the remains, police said.

Rescue workers put up screens around the wreckage to shield firefighters and investigators as they recovered bodies from the blackened shell of the bus.

"Some of the bodies we rescued were very, very small. They must have been very young in age," Piyalak Thinkaew, who led the search, told reporters at the scene, adding that the fire started at the front of the bus.

"The kids' instinct was to escape to the back so the bodies were there," he said.

Police are hunting the coach driver after he fled the scene, acting national police chief Kitrat Phanphet told reporters.

"The driver is on the run, we will not wait for him to turn himself in -- we will send a team to find him," Kitrat said.

Some of the children who survived suffered horrific burns to their faces, mouths and eyes, doctors treating them told local media.

The bus was one of three carrying children from Wat Khao Phraya Sangkharam school in the northern province of Uthai Thani on a field trip to a science museum in northern Bangkok.

A video posted on the school's Facebook page just hours before the tragedy shows the group of youngsters in orange uniform shirts stopping off at the ancient Thai capital of Ayutthaya.

The disaster is believed to have begun when one of the bus tyres burst on the highway around 12:30 pm (0530 GMT), sending it crashing into a barrier and triggering the inferno, officials said. 

Video footage from the scene showed flames engulfing the bus as it burned under an overpass, huge clouds of dense black smoke billowing into the sky.

- Poor road safety -

Prime Minister Paetongtarn Shinawatra visited survivors in hospital and said the government would pay for medical treatment and compensate the victims' families. 

"As a mother, I would like to express my deepest condolences to the families of the injured and deceased," she wrote on social media platform X.

Meechai Sa-ard, a motorbike taxi driver, heard the noise of the incident from a kilometre away. 

"There was smoke everywhere. Poor children, I heard they were very little," he told AFP.

"I was hoping that god would be kind so that the rain could put the fire out and the kids would survive."

Thailand has one of the worst road safety records in the world, with unsafe vehicles and poor driving contributing to the high annual death toll.

Around 20,000 people are killed every year on the kingdom's roads, according to the World Health Organization (WHO) -- more than 50 a day on average.

A similar bus fire killed 20 Myanmar migrant workers in March 2018, while at least 30 people died when a bus careered off a mountain road into a ravine four years earlier.

The economic losses caused by traffic deaths and injuries amounted to around $15.5 billion in 2022 -- more than three percent of GDP -- the WHO says.