The headteacher of Langdon Park School has said that "out of all his students", Amjol Amol was the "least likely" to be involved in violence. Chris Dunne added that the teenager had been working in Northern Ireland to promote peace in local communities.
A post-mortem is due to take place tomorrow.
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The film had formed part of a commemoration to the Choucair family, three generations of whom died in the fire.
John Nolan, who was found with cigarettes and two lighters, suffered burns on 65% of his body after being alight for around six minutes.
Known as Pily she died in January, seven months after the disaster, having suffered a stroke.