Pupils were evacuated from a special needs school in Blackpool after a fire broke out in a toilet block.
Police are now investigating the incident at Park Community Academy, on Whitegate Drive, at around noon on Wednesday.
“The school had evacuated everyone by the time we got there.”Watch manager Pat Thompson
Watch manager Pat Thompson, from Forest Gate fire station, said: “There was quite substantial smoke damage to the toilets.
“The school had evacuated everyone by the time we got there.”
Firefighters used breathing apparatus to tackle the blaze. Nobody was hurt.
The cause of the fire is still under investigation but Lancashire Fire and Rescue said it looks “likely” to have been started deliberately.
A Lancashire Police spokesman said: “We were called to reports of a fire at a school on Whitegate Drive. The cause is still under investigation.”