Police are speaking to a child about the fire which gutted Beckenham School's library.
Detective Inspector Tom Fitzgerald said today that a child was being spoken to by police about the fire, which started shortly before noon yesterday.
Fitzgerald said he could not provide details because of the sensitive nature of the situation.
Flames and smoke from the fire at the Sandwich Rd school were visible from several kilometres away as nor'westerly winds hampered firefighting efforts.
The fire destroyed the school's library and multi-purpose room.
Residents described thick black smoke and flames shooting out of the roof. One couple said they heard an explosion.
Fire Service acting assistant area commander Mike Bowden said the fire was believed to have started on the outside and spread quickly into the library and an adjoining multi-purpose room, used by an after-school care programme.
The strong nor'westers drove the fire through the roof and it spread from there, he said.
"Our main strategy was to stop the fire spreading into the hall, which we have been successful in doing," he said.
Mark Collins, who lives opposite the school, said the fire quickly grew, fanned by the strong, warm wind.
"It was very fast. We just watched it getting bigger and bigger and bigger,'' he said.
"The wind was blowing the flames into the building itself."
His wife, Colleen Ford, went across to the school to check on a holiday programme being run there.
There were about 30 children on the programme but they had been on an outing when the fire started. They arrived back by bus to find their hall on fire.
School principal Sandy Hastings said the fire was "gutting".
"It's great that it's in the holidays, but you never want to see your school on fire,'' she said.
"It's something everyone in education dreads.
"We'll be up and running at the beginning of school as we planned, just without our library."
- The Press
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