A 20-year-old from Plumtead has been telling London Tonight how he's used the devastating murder of his best friend to turn his own life around.
Rather than be involved in crime, Timi Jogunosimi is ploughing most of his time into a football project, which is helping other vulnerable young people in South London.
Watch Jamie Shepherd's report:
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Defence Minister Tobias Ellwood sais the UK is going through a "dark chapter" .
Among those murdered was Keith Palmer, an unarmed constable who "did his job and never wanted any fuss."
A teenager has been arrested after a mass bomb hoax closed hundreds of schools across the UK.