A 35-year-old woman has been arrested on suspicion of murdering a woman who was stabbed to death in north London.
The victim, in her 20s, died nearly an hour after she was found wounded in Belmont Street, Chalk Farm, at 23:10 BST on Sunday.
Two other women were discovered with slash wounds. They were taken to hospital but their injuries are not believed to be life-threatening.
The Met said the arrested woman was in custody at a London police station.
The victim's next of kin have been informed and a post-mortem examination will take place in due course.
Terry Ellis, from Camden Against Violence, said he understood the attack was the result of "an argument" which the woman "wasn't really involved in"
"She was just in the wrong place at the wrong time," he said.
Floral tributes have been laid on the street by friends of victim.
One, who gave her name as Ronney, described the woman as a "really, really good mum" who had a son.
"She was part of everyone's life, she helped everyone," she said.
The killing was the second in two hours in north London after a man was shot dead on Malden Road in Kentish Town.
Police have said there is no link between the two deaths.
Another man was shot dead in Sydenham, south-east London on Sunday afternoon.