A 20-year-old man has been arrested over the fatal stabbing of a teenager who was attacked by a gang in central London.
Hani Abou El Kheir, 16, died from multiple stab wounds in a suspected drugs-related attack in Lupus Street, Pimlico, on Sunday.
The suspect, arrested in north London in a dawn raid, is being held on suspicion of murder.
Detectives think at least 10 people were involved in the attack.
The teenager, who lived on the nearby Churchill Gardens estate, died at King's College Hospital.
Det Ch Insp Neil Attewell said they had already spoken to a number of witnesses to what was a "horrific and sustained vicious attack".
"The tragic events of last Sunday have left Hani's mother and wider family completely devastated," he said.
"Hani's mother has lost her only child and is still coming to terms with the heartbreaking events that have led to the death of her son."
Directly appealing to the parents and carers of those who are thought to be involved, he said: "If you have slightest indication that your child may have been involved in this incident I encourage you to get them to hand themselves in to the police."