A 15-year-old boy has been arrested after a teenager was stabbed to death in a street attack.
The 18-year-old victim was found badly wounded in Neasden, north-west London, at 3.50pm on Friday.
Paramedics fought to save the boy but he was pronounced dead at the scene in Tanfield Avenue from multiple stab wounds, Scotland Yard said.
Police confirmed his next of kin had been informed and a post-mortem will take place in due course.
The 15-year-old is being questioned by detectives on suspicion of murder.
A Met Police spokesperson said: "Police were called at 15:50hrs on Friday, 6 October, to reports of a male stabbed in Tanfield Avenue, NW10.
"Officers and London Ambulance Service attended the location and found an 18-year-old male suffering from multiple stab wounds.
"Despite the efforts of attending officers and LAS crews, he died at the scene."
A crowd gathered around the victim soon after the attack, according to police, and detectives are appealing for those who witnessed what happened or saw those involved leaving the scene after the attack to get in touch.
Those with information should call 020 8785 8244 or to give information anonymously call Crimestoppers on 0800 555 111.