YOUNGSTERS are thought to be responsible for an arson attack on a school in Poole.

A portable building used for general storage and as a caretaker's workshop was partially destroyed in the early morning blaze at Broadstone Middle School.

Three fire extinguishers were let off in the damaged room, although it is not yet known if the extinguishers were being used to tackle the fire or simply to add to the mess created.

Headteacher Marilyn Warden said the mobile room had been condemned and was due to be demolished.

However, it was being used to store cloakroom items, furniture and tools, many of which were lost as a result of the blaze yesterday at 6.15am.

A motorist raised the alarm after spotting flames as he drove past the school in Dunyeats Road.

Fire crews from Poole and Wimborne put out the blaze.

"Three fire extinguishers were set off. We don't know if they were being used to put out the fire or to make a mess," she said.

"At the moment police suspect some older children were involved."

Miss Warden said the fire had not affected teaching at the school.

Pc Pat Waller, of Gravel Hill police station, said: "This was a serious attempt to destroy the workshop and it is being treated as arson. The fire could have spread to neighbouring trees and houses.

"It looks as though whoever started the fire had second thoughts and tried to put it out with a white powder fire extinguisher but failed."

He added: "We don't think the motive was burglary because there were tools and electrical equipment in the workshop that were not taken.

"I would appeal to anyone who saw anyone acting suspiciously in the vicinity of the school to get in touch.

"I would also like to hear from parents who had youngsters coming home with white powder on their clothes, or youngsters who have been behaving out of character or in an unusual way."

Pupils are being given letters to take home to their parents asking for any information regarding the cause of the fire.

If you can help call Gravel Hill police on 01202 696262 or Crimestoppers 0800 555 111.