Just before 10pm, last night, Friday 12 December, two masked men entered the premises armed with a suspected firearm.
They threatened members of staff and ordered them to lie on the floor.
They made off with a sum of cash.
No one was injured however, staff were left very badly shaken by the incident.
Detective Constable Mark Holmes said: “I would appeal to anyone who may have witnessed this incident or who has any information to contact Detectives at Bangor on the non-emergency number 101.
“Or, if someone would prefer to provide information without giving their details they can contact the independent charity Crimestoppers and speak to them anonymously on 0800 555 111.”