Two men, armed with a bat and a knife, entered the premises on the Gilford Road in Portadown last night, Monday, April 11 around 9.40 pm.
The men then threatened staff members before making off with a sum of cash and a quantity of cigarettes which they carried in plastic bags.
The robbers wore hooded tops, scarves and gloves and made off on foot in the direction of the Carrickblacker Road.
The staff members were left shaken but not physically injured following the incident.
Detective Constable Robinson has appealed for anyone with any information about this incident to contact detectives in Lurgan on 101 or Crimestoppers anonymously on 0800 555 111.