A teenager has died after three people were attacked with a knife in the same area in south London.
Paramedics were unable to save the victim, thought to be in his late teens, after being called to Brighton Road, Croydon, on Thursday.
Another teenager, also stabbed, was found nearby and a third teenager was later found with a slash wound close to Purley Railway Station.
He was arrested on suspicion of attempted murder and taken to hospital.
The Met has now launched 11 homicide investigations in the last fortnight.
Emergency crews were called at about 21:15 BST, with police and London's Air Ambulance also attending.
"Despite their efforts, a male, believed to be in his late-teens, died at the scene at 21:50," a Met spokesman said.
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A number of crime scenes in Brighton Road have been cordoned off, and a section 60 order has been put in place, giving police special search powers.
The second stab victim is also being treated in hospital, where his injuries are not thought to be life-threatening.
Police said two other men, whose ages have not been released, were arrested on suspicion of possessing an offensive weapon and are being held in custody.
In a separate attack on Thursday night, a man aged in his 40s was taken to hospital in a critical condition after he was shot in north-east London.
No arrests have been made over the attack, which took place at about 23:00 in Malvern Drive, Woodford Green.
Emergency crews were also called to Barking Road in Canning Town, east London at 07:40 on Friday.
A man aged in his 20s was found stabbed multiple times near the junction of Ordnance Road.
He was taken to hospital. The Met said it was still waiting for confirmation about his condition.