A gang of men have been caught on CCTV attacking a 16-year-old boy with a baseball bat before the teenager was later found stabbed in the head.
The victim, who was walking with a friend, was approached by the group of four men before they chased him along Edgware Road, in Barnet, north London, and attacked him on November 1.
He was found at 5.26pm with two stab wounds to his head, concussion and a missing tooth near a block of flats in Tyrrel Way, several miles away from where he was assaulted.
The boy was taken to hospital where he had surgery for a three-inch wound, the Metropolitan Police said.
The suspects are described as black men, of slim build. One was wearing a dark top with a reflective strip on the hood, light-coloured trousers and a baseball cap and is seen carrying the baseball bat.
Another is seen wearing a dark grey top and black trainers, while a third was wearing a black coat over a grey top with a reflective strip on the hood, grey jogging bottoms and was also carrying a black bag.
The fourth suspect, who is not seen on CCTV, was wearing a maroon jacket, black trousers and white trainers.
Police appealed for witnesses to the incident on Sunday November 1 between 5pm and 5.25pm to contact Barnet CID.