Detective shot during chase after van robbery: Automatic weapon fired at surveillance team. Terry Kirby reports

A FLYING SQUAD detective was recovering in hospital with a head wound last night after a suspected armed robber fired a machine pistol at police during a high-speed chase.

The use of an automatic weapon is likely to increase alarm among senior police officers at the spread of firearms; although semi-automatic and automatic weapons have been seized, yesterday's incident is believed to have been the first in which one has been fired at officers.

Last night, four people - three men and a woman - were being questioned by Scotland Yard detectives about the robbery and shooting in south-east London yesterday morning. The Flying Squad officer, Detective Sergeant Michael Stubbs, 43, is expected to make a full recovery.

According to Scotland Yard, the incident began when two men robbed a Security Express van outside a branch of Barclays Bank in Sidcup, Kent, stealing an estimated pounds 20,000. As the two men sped off in a stolen Vauxhall Astra, they were pursued by Flying Squad officers who were keeping the robbers under surveillance.

A short distance away, the robbers stopped a Ford Capri and forced the female driver out at gunpoint; she was shocked but unharmed. Still pursued by police at high speed, one of the robbers leaned out of the window of the Capri and fired a burst from the machine pistol at the police car, which was hit many times.

The car stopped so that the police could help their injured colleague; the other three occupants of the car were also struck by flying glass. Although the police officers were armed, they did not return fire.

Denise Freshwater, 26, a hairdresser working nearby, said: 'The man was hanging right out of the car window and firing a machine gun along the street. He wasn't aiming at one particular thing, he was just firing everywhere. Anyone on the street could have been hit. I couldn't believe it. There was this man just shooting all over the place.'

Although some witnesses maintained that the shots were fired from the Astra, Scotland Yard said that they had been fired from the Capri.

The Yard said that a short distance away from where the shots were fired, the robbers abandoned their vehicle and fired another series of shots at two uniformed unarmed officers who approached them. They escaped on foot; the officers were uninjured.

A short while later, police surrounded a house in the Greenwich area of south-east London and two men were arrested. The machine pistol, two other firearms, ammunition and the stolen cash were recovered. Two more people, a man and a woman, were arrested at another address in the area during the afternoon. All were being questioned last night.