Men smashed the glass in the door of West Haddon Post Office and broke into the shop.
The incident happened on Wednesday January 18 and police say that sometime between 3am and 3.15am, two men smashed the glass of the front door with a hammer and entered the building, triggering the alarm.
They were then confronted by a member of the public and ran off towards Station Road.
The first offender is described as a 5ft 8in white man in either his late teens or early 20s, wearing a dark hooded jacket with the hood up and a scarf around his face, dark trousers and trainers. He was carrying a Lidl carrier bag. The other offender was a 5ft 6in man, also in either his late teens or early 20s, wearing a blue jacket with the hood up and a dark scarf around his face, dark trousers and black trainers. He was carrying a Tesco carrier bag.
Anyone with information can contact Northamptonshire Police on 101. Alternatively, they can call the independent charity Crimestoppers anonymously on 0800 555 111.