It happened at the Esso Service Station on Warminster Road.
Wiltshire Police are appealing for witnesses after a knifepoint robbery at a shop in Westbury.
Officers were called at approximately 10.30pm on the 11th of March, to a report of a robbery at the Esso Service Station in Warminster Road, Westbury.
A man had entered the store, threatened a staff member with a knife and made off with approximately £200 cash.
Nobody was injured.
The man is described as white, possible bald or with a shaved head, wearing a thick black or dark blue jacket, blue jeans and black shoes with white soles.
He ran off up the hill in Orchard Road.
Officers attended and a search was carried out.
Nobody matching the description was located and enquiries are ongoing.
Detective Inspector Nick Mawson, from Central CID, said: “We know this incident will be alarming to the public, and it was obviously a frightening experience for the member of staff involved.
“We are still at a very early stage of our investigation, but we will of course be considering whether this is linked to recent similar crimes in Trowbridge and Winsley.
“I would urge anyone who was in the area at the time and witnessed anything suspicious, including seeing a man matching the description of our suspect, to call us immediately.”
Anyone with information should call Central CID on 101 and quote crime reference number 54190024417.
Alternatively you can call Crimestoppers anonymously on 0800 555111.