Police are investigating a suspected arson attack

The incident happened in Campbell Road, Caernarfon.

Officers were called to the scene at 2336 BST on Sunday by a member of the public who had heard a loud bang and an alarm going off.

When police arrived, a transit van owned by Gwynedd Health Authority was on fire and another vehicle was damaged.

The injured boy, who is 16, was taken to hospital at Ysbyty Gwynedd in Bangor.

Forensic

He was later transferred to the specialised burns unit at Alder Hey Hospital in Liverpool where he is being treated for burns to his hands, arms and face.

Both of the vehicles involved have been seized by police for forensic examination.

A North Wales Police spokesman said they were investigating the fire as arson and were waiting to speak to the boy.

They are appealing for witnesses but are not looking for anyone else in connection with the incident.