A 14-year-old boy was among two people to be arrested on suspicion of murder after a man was stabbed to death in east London.
The victim, aged in his 20s, was pronounced dead in Clarence Mews, Hackney, at 14:30 GMT on Thursday.
Police believe he was killed during an “altercation” involving several people and “at least two other suspects remain outstanding”.
The boy and a 26-year-old man remain in custody at an east London.
Speaking about the killing, Det Ch Insp Paul Considine said “another young man’s life had been tragically cut short due to the violent actions of others”.
“I would urge anyone who was in the area and witnessed this incident to come forward and speak to police,” he said.
A man was stabbed to death in a south-west London street by the person he had been walking with, police have said.
Tesfa Campbell, 40, was found by police responding to reports of a fight on Latchmere Road in Battersea on Wednesday. He died in hospital.
Det Ch Insp Simon Harding, from The Met, said it is believed Mr Campbell was walking on Burns Road with another man who stabbed him and fled on foot.
No arrests have been made in connection with his death.
Police found Mr Campbell injured at about 14:45 BST and have appealed for witnesses who were in the area at the time, “particularly” around the nearby Latchmere Leisure Centre.
Det Ch Insp Harding said: “This stabbing happened in broad daylight and we believe there are people out there who can help us establish the facts of the incident.”
A post-mortem examination of Mr Campbell, who was from Croydon, will happen in due course.
A man has been arrested after a gun was fired outside a mosque in east London during Ramadan prayers.
Police were called to reports of a man with a firearm entering the Seven Kings Masjid in Ilford at 22:45 BST on 9 May.
A 28-year-old man was arrested earlier on suspicion of possessing a firearm with intent to cause fear or violence, possession with intent to supply, and assaulting a police officer.
Evidence suggested the weapon was a blank-firing handgun, police said.
Nobody was hurt in the incident. The arrested man remains in custody.