The knife point robbery happened at a shop in the Central Promenade area of Newcastle last night, Tuesday, October 27.
Police say that sometime after 8.25 pm, two staff members found a man in private quarters of the shop.
He was armed with a knife and took some money and a staff member’s mobile phone.
He also got one of the staff members to carry a safe outside.
But the staff member dropped the safe in the street and the man made off on foot.
Detective Inspector Graham said: “I would appeal to anyone who saw this man or who knows anything about this incident to contact Downpatrick Police Station 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.”