An alert caretaker has been praised for preventing a potential explosion at a packed high school.

Intruders turned on all the gas taps in two science laboratories at Clacton County High School.

Caretaker Steve Moore spotted the smell on his usual rounds just after 9pm and immediately turned off the taps and called the police.

But had he turned on the light switch when he went to investigate, the building could have been blown sky high.

John Clay, head teacher at the school, was relieved that Mr Moore had carried out the correct procedure.

"This could have been serious and we could have had a major incident on our hands," he said.

"There were a large number of adults on the premises at evening classes and had Steve flicked the switch I dread to think what might have happened.

"It was getting dark so he could easily have put the light on - but fortunately he carried out the procedure to the letter. It was only his normal nightly check which discovered that someone had got in and it was lucky it had not happened after that time. "

Mr Clay had been on the premises - in a classroom below the science laboratories.

Brian Bennett, station commander at Clacton Fire Station, said officers went to the school and helped ventilate the building.

"Like any build-up of gas you only need a spark in the right conditions and it is a recipe for disaster," he said. "It would have been a volatile situation and could have had much more serious consequences."

Mr Clay said staff were now searching through video tapes from the school's security surveillance cameras in the hopes of identifying the intruders.

He said it was not clear at this stage who had been responsible.

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