Police believe a young woman killed while celebrating her birthday was an innocent victim, "caught in the wrong place at the wrong time."
Sabrina Moss, of Neasden, north west London, died in hospital after being involved in a double shooting.
Another 24-year-old woman is in hospital. Her injuries are not thought to be life-threatening.
Detective Chief Inspector John Sandlin of the Metropolitan Police said: "Enquiries continue to establish the full circumstances of this tragic incident.
"At this early stage, I believe the two women were innocent parties who were caught in the wrong place at the wrong time."
Scotland Yard said officers were called at 4.12am yesterday to reports of shots fired in the street in Kilburn High Road, Kilburn, north west London, at the junction with Messina Avenue.
Police and London Ambulance Service found two women suffering from gunshot injuries and both were taken to London hospitals. Ms Moss was pronounced dead later.
Two men have been arrested by police in connection with the killing.
Sandlin said: "I am appealing for anyone who witnessed the shooting, or who saw anything suspicious in the Kilburn area, to call police.
"In particular, I need to hear from anyone who saw two males who came into the High Road from Messina Avenue and, after the shooting, made off on foot back along Messina Avenue."
Tributes to Ms Moss flooded onto social networking site Twitter, with many of her friends and family reporting that she had a young child.
Anyone with information that might assist the investigation was asked to call the incident room at Hendon on 020 8358 0300. To remain anonymous, call Crimestoppers on 0800 555 111.