THREE passers-by could hold vital clues in the hunt for a gunman who tried to hold up a County Durham post office.

The attempted armed robbery took place at about 2pm on Tuesday, when the man burst into the post office in Quebec Street, Langley Park, near Durham, brandishing a gun and demanding cash.

He fled empty-handed when the woman behind the counter sounded the alarm.

Detectives have established that the crook waited in side streets near his target for ten to 15 minutes beforehand.

They believe he delayed the attempted robbery until he was sure there were no customers inside the post office.

Investigators think three people saw the man during this time and are urging them to come forward. They are keen to trace a woman with blonde hair who used the post office and left with a male companion. They passed him as they walked up the lane connecting Quebec Street and South View.

Police would also like to speak to another woman who passed the robber at the rear of the post office a few minutes later.

Det Sgt Vic Deanes of Derwentside CID said: "All three people are potentially very important witnesses and I would like them to contact me or any of the officers involved in the case."

The robber is described as white, in his early twenties, about 5ft 8in, slim to medium build.

He had a pale complexion with sharp features and was clean shaven. He spoke with a local accent and was wearing a dark coloured, padded, waist-length coat with light coloured trousers.

Anyone with information about the crime should contact Derwentside CID at Consett police station on (01207) 504204.