A young woman was killed when a bullet ricocheted off a wall and hit her in the back as she stood in the heart of gang territory, a court heard.
Mohanna Abdhou, 20, known as Montana, was caught in a hail of gunfire from two masked men on bicycles, a jury was told.
The alleged killers Mohammed Tawfik, 19, and Kylann Grannum, 21, were helped by a 17-year-old boy who provided them with a bike and a place to change, the Old Bailey heard.
The three defendants are on trial for murder alongside Grannum's girlfriend Kathleen Peddar, 21, who is accused of assisting the alleged gunmen to evade capture in the hours after the shooting.
Prosecutor Anthony Orchard QC said the victim was killed on the evening of May 26 last year on the South Kilburn Estate, in north west London.
He said: "Mohanna was shot by two masked gunmen who approached, riding pedal cycles, the group she was with.
"At least three, probably more, shots were fired in the direction of her group.
"One bullet ricocheted off a wall and hit Mohanna in the back, severing her pelvic artery. She died at the scene."
Miss Abdhou, of Hayes, was not believed to be a specific target of the shooting.
Mr Orchard told jurors the killing followed years of tit-for-tat violence between two rival gangs whose territories lie just half a mile apart.
The Mozart Estate is the home turf of the Harrow Boys or HRB who had a long-running dispute with a gang known as Killy or SK from the South Kilburn Estate.
The prosecutor said Tawfik and Grannum were linked with HRB while the 17-year-old defendant mixed with people from the same gang.
He said the shooting took place while the victim was standing in the middle of the South Kilburn Estate, the heart of the rival gang's territory.
Tawfik, from Kilburn, Grannum, of no fixed abode, and the youth, who cannot be identified, have pleaded not guilty to murder.
The youth also denies assisting offences and Peddar, of Brent, north west London, denies two counts of assisting an offender.