The hunt is on for an armed robber who threatened staff with a claw hammer before stealing £2,000 in cash from the Co-operative store in Clayton-le-Moors.
The incident happened at about 10.45pm on Friday, January 14, when a man entered the store on Pickup Street wearing a dark scarf and clothing to hide his identity.
Detective Sergeant Simon Upton of Accrington CID is now appealing for witnesses.
He said: "This was a terrifying ordeal for all the staff and customers who were present when this offence took place. I have no doubt that this male is probably a local man who will now have a significant amount of money at his disposal.
"I urge anybody who witnessed this robbery, anybody who has any information as to who was involved or anybody who saw anything suspicious just prior to the offence to come forward. Any information no matter how small may help us to identify this person so they can be brought to justice."
The offender is described as a 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.
Anyone with information should contact police on 01254 51212 or Crimestoppers on 0800 555 111.