A 17-year-old boy and a man have been arrested over a fatal stabbing outside a south-west London Tube station.
Malcolm Mide-Madariola, 17, from Peckham, was killed outside Clapham South station on Friday afternoon.
The Metropolitan Police said a boy the same age and an 18-year-old man had been arrested on suspicion of murder.
The attack happened within minutes of an "altercation" between two groups of boys, police said.
Det Ch Insp John Massey added that many witnesses had already come forward but appealed for more to do so.
A post-mortem examination is due to be held at St George's Hospital Mortuary.
Police do not believe Malcolm's death was gang-related.
Malcolm, a student at a college in Clapham, was the second teenager to be stabbed to death in south London within 24 hours.
Jay Hughes, 15, died on Thursday night after being stabbed in a chicken shop in Randlesdown Road, Bellingham.
No arrests have so far been made in that investigation.