A teenager was shot dead as he ran through a housing estate in south-east London trying to escape a gunman, neighbours said.
The 17-year-old victim died in a stairwell at a block in Peckham on Wednesday afternoon.
Witnesses said he was desperately banging on the closed door of one eighth-floor flat before the fatal shot rang out. Two other teenagers, one aged 17 and another 18, suffered stab wounds as a group of young men ran amok on the estate.
Detectives from Scotland Yard's Trident unit were investigating whether the murder and stabbings took place during a clash between rival gangs.
Three male suspects, all believed to be aged in their teens, were arrested at the scene and were being questioned at south London police stations. The gunshot victim was found dying in a stairwell at Heron House after reports of an attack at about 4.30pm on Wednesday. He was pronounced dead at the scene.
Police were then led to a 17-year-old boy with a stab wound who had run to a flat in nearby Gannet House. He was taken to hospital where his condition is stable. Hospital staff then called police to report a third victim, an 18-year-old man, who arrived with minor stab injuries. He has been discharged.
Samba Koroma, 40, a cleaning manager, said the dead teenager was seen banging on the door of an eighth-floor flat. He said: "He ran into the building. He was knocking on that door for somebody to open up but nobody opened the door. I don't know whether the boy knew the couple (who live there). He ran down the stairs and I think that's when he got shot."
Police sealed off several areas on the estate as officers in forensic suits searched bushes and open ground.
Camberwell and Peckham MP Harriet Harman has visited the scene of the shooting to speak to police and residents. She said: "My deepest sympathies are with the parents and the family of the young man who has been killed.
"It is vital that those who committed this brutal crime should not get away with it. The overwhelming majority of young people in this area are decent, hardworking people who want to make the most of their lives and people are dismayed that once again a tragedy has cast a shadow over Peckham."
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