A Denny bookmakers has been robbed for the second time in five days.
Officers believe the "violent and callous" incident at William Hill in Stirling Street on Wednesday is linked to the previous robbery on 7 April.
The latest robbery happened at about 19:45 when two men entered the premises and repeatedly threatened a member of staff and two customers with weapons.
They left with a sum of money and were last seen entering a passageway leading to Herbertshire Street.
Both suspects wore high visibility jackets and hard hats, with their faces covered by dark scarves during the incident.
Police said no one was injured as a result of the robbery.
Det Insp Jim Thomson said: "This was a violent and callous incident which has left the three victims badly upset.
"This also follows a previous robbery at this bookkeepers last Friday, which we are still investigating and believe to be linked to this most recent incident."
The first suspect was described as white, about 6ft tall, of medium build, with a light tan, and spoke with a local accent.
The second man was described as white, of medium build and about 5ft 9in tall.