Two armed men robbed a ‘large amount of money’ from Aylesbury Service Station on Monday morning.
The men were armed with a knife and what is believed to be a firearm, which was hidden under a cloth at the time of the hold up.
It happened just before 8am outside the station on Bicester Road.
A cashier in his fifties was working in the petrol station at the time of the robbery but was not injured.
Police are hunting two black male suspects.
The first is aged between 30 and 35 years old, well built, wearing a woolly hat with a black cap over the top, a red jacket with white stripes on the sleeves, black trousers with a white stripe down each side, white trainers, and a pair of black builders gloves with blue fabric on the palms. He also had diamond stud earrings in each ear and was carrying a black bin bag.
The other was around 30 years old and wearing a black cap, black top and denim jeans.
Police would not say how much money was taken or even whether it was in the hundreds or thousands.
Anyone with information is asked to contact police via the enquiry centre on 101 or Crimestoppers anonymously on 0800 555 111.