The incident took place at the Spar store in the market place, in Wolsingham, at about 2.45pm yesterday.
SCENE: Outside Wolsingham Spar this morning Video: SARAH CALDECOTT
Durham Police said a man described as being in his 20s, wearing glasses and a grey hoodie threatened staff before making off with a small amount of money from the till.
Caroline Embleton, manager of the shop, said: “Staff were shocked but are fine.”
She was one of five members of staff in the store at the time of the incident.
The force is now appealing for anyone with information relating to the robbery to come forward.
Anyone with any information should contact Durham Police on 101 quoting incident number 207 of October 30.