A neighbour said she heard a girl's screams but didn't realise what was going on.
Ronke Phillips reports.
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The child is in a serious but stable condition in hospital.
A 19-year-old man has been on suspicion of attempted murder in connection with the shooting of a two-year-old and three adults in Harlesden
Face coverings will be compulsory on public transport from June 15, Transport Secretary Grant Shapps has said.