AN off-duty police officer was threatened at gunpoint following a failed attempt to rob a post office.

Last night four men were in custody following the incident earlier in the day.

At 10am yesterday, three men wearing balaclavas, one of whom was brandishing a hammer, burst into the post office in Front Street, Shotton Colliery, east Durham, only seconds after an unspecified amount of money was delivered.

One man, who had been leaving the shop, was pushed back inside by the gang and an elderly man, one of three customers in the post office, was knocked to the ground.

The robbers threatened two female members of staff and demanded the money that had just been delivered.

The staff triggered alarms and the robbers fled empty-handed.

An off-duty police officer, who was in a neighbouring shop, heard shouts that the post office was being robbed, and when he saw men running down the street, chased them.

Despite being threatened with the hammer, when he continued the pursuit, one of the suspects shouted "shoot him".

One of the raiders then produced a handgun and pointed it at the officer from about 20ft away.

The officer stopped and the gang got away in a blue BMW.

A burnt-out car was found shortly afterwards in Ludworth, about three miles from the scene of the attempted robbery.

Armed officers later went to a house in Barnard Avenue, in Ludworth, and at about 11am, four men were arrested.

They are being held for questioning.

Detective Chief Inspector Jeff Watson, who is leading the investigation, urged anyone who saw the attempted robbery to get in touch.

Anyone with information on the incident is asked to call 0191-586 2621 or Crimestoppers in confidence on (0800) 555111.