Three men stole cash and cigarettes from a Northampton convenience store.
The men threatened a cashier at Weedon Road Mini Market in St James with a knife when they entered the store just after midnight on Friday, March 25.
They are all described as white and were all wearing masks, hooded tops and dark trousers.
Witnesses or anyone with information is asked to call Northamptonshire Police on 101.
Alternatively, they can call the independent charity Crimestoppers anonymously on 0800 555 111.