An ATM machine and a safe were taken during the heist at the shop on the Crossgar Road in Ballynahinch.
Detective Sergeant Bell said “It was reported that an ATM machine with a substantial amount of money was taken as well as the safe from the commercial premises.
“It is believed that the incident occurred sometime before 4.30 am this morning.
“I would appeal for anyone who may have witnessed any suspicious persons or vehicles in the Crossgar Road area to contact Detectives on the non-emergency number 101 quoting reference 16224/04/18.
“Alternatively, information can also be provided to the independent charity Crimestoppers on 0800 555 111, which is 100% anonymous and gives people the power to speak up and stop crime.”