Monkwearmouth School has been shaken by the deaths of two students and one former pupil, all of whom were found dead in burnt-out buildings.
The police have ruled out foul play, and senior officers are working on the theory that the deaths involved drugs, solvent abuse and experiments with fire.
Jim Farmie, head of the 1,400-pupil comprehensive, will today attempt, with his staff, to forge a new strategy against solvent abuse.
The charred body of David Grieff, 15, was found in a burnt-out shed on allotments off Newcastle Road in Sunderland on Friday night. This followed the death of David Hanson, 15, who was in the same year, whose body was found in a blazing derelict building half a mile away, on 8 February.
The body of Thomas Kelly, 18, a former Monkwearmouth pupil, was discovered on 26 November in a burnt-out shed close to the Newcastle Road allotments. He is believed to have been acquainted with the other victims.
Louise Bramfitt, chairwoman of Sunderland social services, said: 'My first reaction is to sympathise with the families affected by these tragedies, but there is also a need to reassure other parents by perhaps giving guidance about solvent-abuse symptoms.'
Norman Bohill, a Conservative councillor and a school governor, said: 'I am deeply concerned about these tragic deaths. Monkwearmouth is not a bad school - it is probably one of the city's best.'
Detective Chief Superintendent Barry Stewart, head of Northumbria CID, said he was satisfied that foul play was not involved in any of the deaths, but he added that they were sufficiently suspicious to cause concern.
Police have appealed to anyone with information regarding this 'new craze' to come forward. It is thought that some teenagers are using matches or lighters to heat up substances they want to inhale.
The deaths will add to fears that schoolchildren are willing to experiment with an ever-increasing list of readily available solvent products. Re-Solv, the Society for the Prevention of Solvent and Volatile Substance Abuse, says a wide range of household products, including deodorants, hair-sprays and lighter fuel, are abused.