The hunt is on for an armed robber who threatened staff with a hammer before stealing cash from the Co-operative store in Clayton-le-Moors.
The incident happened at around 10.35pm on Wednesday, February 9 on Pickup Street when a man entered the shop demanding the tills be opened.
Detectives are linking the case with an incident that happened last month when a hammer-wielding robber stole £2,000 in cash from the same shop.
DS Paul Langley said: "This is the second time this store has been targeted in a month and we are linking both robberies.
"I would appeal to anyone who was in the area and witnessed anything suspicious to come forward and contact police. Although nobody was hurt in this incident, the staff have been left physically shaken following their ordeal."
After robbing the store on Wednesday the man then left the shop and headed towards the car park on Wellington Street.
He is described as white around 5ft 11 and was wearing a black jacket, tracksuit bottoms and trainers. It is thought his accent was not local to the area.
The armed robbery which took place on Friday, January 14 happened at about 10.45pm.
The offender was described as white, around 6ft tall and slim. He was aged mid 20s to early 30s, spoke with a local accent and was wearing a dark jogging top with the hood up.
A dark scarf was used to hide his identity and he was also wearing dark coloured jogging pants and black trainers. Police say he was also wearing black woollen gloves.
DS Langley added: "If anyone has any information that can assist our investigation then I would ask them to contact us."
Anyone with any information about any of the two incidents should contact police on 08451 25 35 45 or Crimestoppers anonymously on 0800 555 111.
