Two teenagers have been shot in front of families with young children in a McDonald's restaurant.
The friends, both believed to be 17, were in the queue on Thursday afternoon when a gunman shot one in the chest and the other in the arm.
The victim hit in the chest is said to be in a critical condition and the other youth is described as stable.
The Met Police's Operation Trident team is investigating the incident which happened in Brixton, south London.
Detective Constable Luis Martinez from Operation Trident, which investigates gun crime in London's black community, said: "The venue was very busy at the time of the shooting and those present - including families with young children - were shocked and terrified by this violent attack.
"We have only a brief description of the gunman at present - he was black and approximately 6ft 1in tall - but if anyone saw the incident or the suspect making off, we need to hear from you."
Police said the suspect ran down nearby Rushcroft Road and into Saltoun Road, heading towards Railton Road.