Three suspects were arrested seconds after a gun shot rang out across the tranquil streets of a historic Sussex town.

The shot was thought to have been fired accidentally by a flying squad officer during the arrest of the three men in connection with a series of cash-in-transit robberies.

It is not yet known where the bullet landed but no one is believed to have been injured.

Neighbours in the normally quiet town of Battle heard a loud bang as seven unmarked police cars suddenly swooped on a white Ford Escort, stopping it outside the Nationwide building society in the High Street yesterday.

The suspects' car was boxed in before specialist crime officers from the Metropolitan Police flying squad pulled the suspects from their car and arrested them.

Bloodstains were left on the road after one of the suspects was led a way with a bandage around his head.

Staff inside the building society were ordered to stay inside the building as officers sealed off the area as a crime scene.

Onlookers said they saw bags of what looked like bundles of cash being confiscated by police.

An investigation is being conducted by the Met's directorate of professional standards and Sussex Police into why an officer discharged his firearm accidentally during the incident.

The dramatic raid stunned neighbours and traders in the sleepy town who are more used to tourists taking over their streets than armed police.

It was the shot, however, which alerted most people to the commotion at the junction of High Street and Mount Street yesterday morning.

The arrests were part of an intelligence led investigation targeting individuals involved in cash-in-transit robberies.

Angela Jackson, 39, of Netherfield Road in Battle, who owns Mrs Brown's Victorian Sweet Shop on the High Street, said: "We are not quite sure what happened, there are so many different stories that someone was shot, someone was killed, there was a robbery, but the shop definitely suffered.

"I was a little late opening up in the morning and tried to come into the town just after 10am and the road was blocked. I couldn't get in from either end so I went home and parked the car, walked through and eventually opened the shop at 12 but it was like a ghost town.

"It's been a bit of an eye opener because I moved here from London four years ago to get away from this sort of thing.

"It is worrying a shot was fired because children are walking around town as are people of all ages and it could have been a very different story."

One eye witness said: "We heard a lot of noise like a riot was happening and then a loud bang."

The Met said two of the men, who were being detained at a police station in East Sussex, were from the area and the other was from London.

The operation began at 9.50am but witnesses had noticed plain clothed police officers in the area.

One witness said: "We didn't know they were plain clothed police officers until it all kicked off and they suddenly put police hats on. They were all armed and you could see their guns."

One staff member at the Nationwide said: "A woman in a red car had been driving in front of the white Ford when the police swooped and she became trapped by the commotion."

Police tape was put up , preventing pedestrians and vehicles from entering the area and High Street and Upper Lake were closed for over four hours.

Paul Bennett, 57, owner of Battle Interiors on High Street, said at one point there were about 60 police officers at the scene. He said: "The unmarked police cars came screeching down the road and blocked them in. I could only see two of the men.

"When the police got them out of the car they pinned them down on the ground and I could see another one was bleeding and he looked like he was in his early 20s.

"The paramedics were not called for about half an hour after it all happened but eventually an ambulance took him away at about 11am. The others were taken away in a police car with a police escort."

Gillian Ball, 54, of Marley Lane, Battle, a teacher at Hastings College, said: "I can't see why if the Met police are going to arrest criminals or suspected criminals they can't at least do it outside a populated area."

Chief Superintendent Nick Wilkinson, East Sussex Divisional Commander, said: "I would like to reassure the local community this is a rare occurrence in Battle. Officers, including police community support officers, will be highly visible in the area to provide ongoing reassurance."