The whole school was forced to evacuate after the mini blaze was started in the girl's toilets just after 10am on Tuesday.

It's thought that 'high-spirited' kids set fire to a toilet roll after finishing their final GCSE exams.

But one student suggested that the fire could have been started by pupils smoking in the toilets.

The incident comes one month after a group of Oriel students 'stormed' the school after teachers scrapped their end of Year 11 celebrations.

Police were then called to reason with teens who formed a peaceful sit down protest on the grounds of the Matthews Drive School.

Headteacher Gill Smith, who was patrolling the playground with a loud speaker, said she would be reviewing CCTV tapes to see who sparked the bathroom blaze.

She said: "All we know is that a fire sensor went off in the girl's toilet and the alarms went off at around 10am.

"Most pupils were in lessons at the time but some year 11 students had just finished exams so there was an unusual amount of movement in the building at the time.

"There is CCTV inside the building and that should have picked something up."

She added: "The kids have been brilliant; they were evacuated quickly and have waited patiently for the all clear to go back into the building."

Two tenders from Crawley attended the fire to make sure all flames had disappeared and to make the scene safe.

A spokesman from West Sussex Fire and Rescue said: "The fire was in the girls toilets after someone set fire to a toilet roll.

"We have had fire investigation to look at the scene but it looks like it was deliberate."

Police and site managers from HBG, the private company which runs the school site, were also at the scene as fire investigators entered the building.

In a letter home to parents, Mrs Smith said: "Students and staff evacuated the building safely, calmly and quickly, grouping in Mentor Groups at the Fire Assembly point adjacent to Matthews Drive, Maidenbower.

"After approximately 45 minutes we were given the all clear from the Fire Service to re-enter the building.

"We are treating this as arson, and have informed the Police accordingly.

"The toilet remains sealed off until forensic officers are able to investigate fully.

"Please be assured, that we take this matter very seriously indeed and are conducting a full and thorough investigation.