A thief stamped on a female member of staff after breaking into a pawnbrokers.
At around 5.40pm on Saturday the man approached the woman who was standing at the rear of Cash and Cheque Express in Buckingham Street, Aylesbury.
He dragged her inside the store and threatened her with what is thought to have been a knife.
The offender pushed the woman to the floor, stamped on her stomach several times and stole money from the safe.
He left the store and got in to a dark blue-coloured car which was waiting in New Street at the junction with Havelock Street.
The victim sustained minor injuries which did not require hospital treatment.
The offender is white, approximately 5ft 5ins, and slim.
He was wearing a black coat, dark-coloured tracksuit trousers, a black balaclava or facial covering and was carrying a black Adidas rucksack.
Investigating officer Det Sgt Tracey Benham, from Aylesbury CID said: “Detectives are working to establish the circumstances of this robbery and are conducting enquiries locally.
“I would like to speak to anyone who saw any suspicious people or vehicles in the area at around the time of the incident.
“I would also like to speak to anyone who has any information about this robbery.
“Please contact the police if you have details which could assist with the investigation.”
Contact police on 101 or Crimestoppers anonymously on 0800 555 111.