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 mother of a boy who is in a critical condition in hospital after he was stabbed in a street attack has issued an emotional appeal.
Police said seven men were arrested during West Ham's EFL Cup fourth round win over Chelsea at the former Olympic Stadium.
Damon Smith, 19, has been charged with making or possessing an explosive substance with intent to endanger life.