A school bus transporting 14 pupils to JCoSS burst into flames early this morning.

The vehicle, which was taking the pupils to the Barnet school from St Albans, was evacuated before the fire took hold. All the passengers escaped unharmed.

The bus caught fire in Radlett at around 7.20am. Witnesses report hearing a loud explosion at the time.

Jeremy Reece, owner of the Little Bus Company, which operates the service, said the fire was caused by an overheated brake drum.

“Our vehicles are regularly maintained and this particular coach was inspected four weeks ago,” he said. “The vehicle was used on Friday and there were no reported problems.”

He added that students were escorted to safely by the driver, Steve Williams, “following standard company policy”.

Parent Bennett Aaron described feeling “helpless” after learning that his two children, aged 12 and 15, were on the bus at the time.

“They texted to say they had been evacuated. I tried getting down there, but couldn’t get through the traffic,” he said.

“My children are OK now but they were incredibly traumatised. The seats where my daughter and her friend were sitting were completely destroyed by the fire. Where they were sitting is now just piles of ash.”

He added: “The driver was incredible. The situation could have been so much worse but because of him, everyone came out safely.”

Photos of the incident reveal smoke and fire coming from the bus, as well as broken glass along its left side.

This was caused by the fire service breaking the windows in order to let out smoke.

JCoSS headteacher Patrick Moriarty said the school would be working with the bus company to ensure the incident was fully investigated.

A school spokesperson said all the children involved had been given the day off to recover.