Four men are being held by police after a gang of crash-helmeted robbers wielding sledgehammers was put to flight by a pensioner who attacked them with a handbag.

Video footage of the attempted robbery at a jeweller's in Northampton town centre showed the unlikely have-a-go-hero crossing a road and jogging briskly towards the six-strong mob as they smashed the shop's windows.

The raiders, who had arrived at the scene on three scooters, drove away just moments after the red-coated pensioner, thought to be aged in her 70s, began lashing out at them with a large black handbag.

The footage of the robbery, broadcast on ITV's Anglia Tonight programme, also showed other members of the public pinning down a man who had fallen from one of the scooters just yards away from the shop.

Northamptonshire Police said officers were called to the scene, on the corner of Gold Street and Bridge Street, at 9.30am on Monday after the offenders began to smash the store's front windows using sledgehammers.

A total of four men, aged 18, 22, 25 and 39, were arrested and police are now seeking a further two other people who are believed to have been involved in the incident.

A police spokesman said: "The offenders were disturbed by members of the public and fled the area without taking anything.

"One of the offenders was detained by members of the public and the other three men were arrested by police a short time later."