Police in Brixton said the man they have arrested following a fatal stabbing where a 28-year-old woman was killed trying to protect her younger sister, is known to them, but would not give any more details.
Speaking this afternoon, Detective Reynolds said young children were at the scene of both attacks, which involved "extreme violence", and officers are trying to establish whether they saw anything significant.
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Tonight western and northern areas will remain a little breezy with a few showers at times.
Leicester are Premier League champions after Tottenham conceded a two-goal lead in a bad-tempered 2-2 draw at Chelsea.
Football fans and players from all over the world savoured Leicester City Premier League triumph on Monday night.