A bus carrying dozens of primary school children has crashed and caught fire just outside Bangkok, leaving over 20 feared dead.

The bus was returning from a school trip in the northern province of Uthai Thani when the tragic accident occurred.

Out of the 41 passengers, 16 children and three teachers managed to escape the burning bus. However, 22 children and three teachers are still missing, according to Thailand’s Transport Minister, Suriya Juangroongruangkit.

Rescue efforts have been hampered due to the intense heat from the fire, and investigators have not yet been able to fully examine the charred vehicle.

Eyewitness reports and photographs from the scene show the bus completely engulfed in flames, with thick black smoke rising as firefighters battled the blaze. Eight survivors were sent to the hospital for treatment, with many suffering from severe injuries.

Transport Minister Juangroongruangkit pointed to the use of compressed natural gas as a key factor in the severity of the fire, labeling the fuel as “extremely risky” for passenger vehicles. He called for a review of regulations regarding its use.

Prime Minister Paetongtarn Shinawatra expressed her deep condolences to the victims’ families, stating, “The government will cover medical costs and provide compensation for those who lost their lives.” She also ordered ministers to visit the site.

The accident is believed to have been caused by a tyre blowout that sent the bus crashing into a barrier on the highway.

Rescue workers confirmed the fire started at the front of the bus, with many of the victims trapped towards the back.

The driver of the bus fled the scene but authorities are confident he will be apprehended soon. The ages of the children onboard range from 3 to 15, but exact details remain unclear.

Thailand is known for its poor road safety record, with roughly 20,000 road fatalities per year.