The incident happened when the men entered Slattery's Garage on the Main Street around 7.30pm yesterday evening armed with a shotgun, threatened staff and demanded money.
Nobody was injured in the incident and no money was taken, however staff were left very shaken and the suspects fled the scene in a car.
Gardai are appealing for anyone who may have seen anything or noticed any suspicious behaviour to contact them.
Detective sergeant Seamus Maher is from Clonmel Garda Station.
