Police who were tipped off about a murder attempt at a nightclub party held for the garage act So Solid Crew parked a patrol car outside the venue in a failed attempt to foil the attack.
An urgent internal inquiry was launched yesterday to establish whether police could have done more to prevent the attack, which ended in the killing of Jason Fearon, 26.
An anonymous caller rang Crimestoppers last week with "specific" information about a gang planning to shoot their rivals at the Turnmills night-club in Clerkenwell, north London, on Easter Day.
The tip-off was passed to local police who asked for the party, held to launch the solo single of the So Solid Crew singer Lisa Maffia, to be cancelled. When promoters refused, officers parked an empty police car outside the club.
Early on Monday, eight black men burst into the club and fired several shots, injuring a man in the shoulder. Two men fled in an Audi TT sports car, pursued by gunmen in a BMW who fired dozens of shots with automatic handguns as they leant out of the windows.
Mr Fearon, the passenger in the Audi, was hit in the head and died at the scene. The Audi driver was arrested and later released on bail. The two gunmen and their associates escaped.
The Metropolitan Police Deputy Commissioner, Ian Blair, has launched an internal investigation into the incident to be headed by a deputy assistant commissioner. Mr Blair has asked Sir Anthony Burden, Chief Constable of South Wales Police, to oversee the inquiry.
A Scotland Yard spokesman said: "The review will focus on the handling of intelligence and action taken following receipt of information prior to his murder. We accept that there are some lessons to be learnt but do not wish to pre-empt the outcome of the review." The force has referred the matter to the Police Complaints Authority.
The call to Crimestoppers was passed to the Operation Trident task force, which deals with black-on-black crime. The tip was anonymous and did not name the gunmen.
A Scotland Yard spokesman said: "Crimestoppers handled the information accurately and efficiently, and passed that information to the appropriate department, which was Operation Trident. The review will not be focusing on the actions of Crimestoppers."
So Solid Crew have been associated with gun crime. Two people were shot at a birthday party and show staged by the group at the Astoria theatre in central London in October 2001.