Staff at a bookmaker's store in Corsham were threatened with what police believe to be a small gun during an armed robbery.
Police were called to William Hill in the Newlands area of the town following reports of the incident on Wednesday evening.
A force spokesman said a man handed staff a yellow bag and ordered them to empty the till.
He is described as 5ft 10in, of medium build and spoke with a local accent.
Police believe the man was in his early 20s and was wearing a black-hooded coat, gloves and dark trousers.
They said another man, who was stood in the door during the attack, was wearing dark clothing except for white trainers.
A third man police want to speak to in connection with the incident was seen in the shop earlier on Wednesday.
"[That] man pictured in the CCTV was known to be in the shop earlier in the day and we are very keen to speak with him in connection with this incident," the spokesman said.