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 in Kilburn, north-west London on 26 May.
The alleged killers Mohammed Tawfik, 19, and Kylann Grannum, 21, were helped by a 17-year-old boy, the Old Bailey heard.
The three all deny murder.
Mr Grannum's girlfriend Kathleen Peddar, 21, from Brent, is accused of assisting the alleged gunmen to evade capture in the hours after the shooting.
The 17-year-old boy, who cannot be identified, provided the alleged killers with a bike and a place to change, the Old Bailey heard.
Both deny assisting Mr Tawfik, from Kilburn, and Mr Grannum of no fixed abode.
Prosecutor Anthony Orchard QC said: "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 on the South Kilburn Estate.
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.