A teenager has been arrested in connection with the shooting of a man by an armed motorcyclist, Scotland Yard said.
A 17-year-old boy was arrested in Cambridge by detectives investigating the death of Nathan Foster, 18, in Brixton, south London.
A Metropolitan Police spokesman said the teenager, who was arrested at about 10pm on Wednesday, is in custody in Cambridgeshire.
The youth is the second person to be arrested in connection with the shooting in Marcus Garvey Way last Friday.
A 14-year-old arrested on Saturday has been released on police bail, Scotland Yard said.
Police believe there are people in Brixton who may know the identity of the killer who have not come forward.
Mr Foster was part of a group of up to a dozen youths of a similar age gathered in the cul-de-sac when the shooting took place. They were approached by a teenager on a motorbike or moped who spoke to several people before producing a gun and firing towards them.
One line of inquiry is believed to be that a row was sparked over a piece of jewellery.
The gunman is thought to be aged about 18. He was on a blue motorcycle or scooter and wearing a helmet.
Mr Foster was taken to hospital but died at about 11pm. His death brought the number of teenagers murdered in London to 17 this year.
