Police responded to a call at around 12:15 this morning about an assault in progress at the store located on 3rd Avenue in Sunset Park.
When police arrived, they found a man in his fifties on the floor with trauma to his head.
EMS was also called but the victim was pronounced dead at the scene.
The exact cause of death is unknown but police believe this was the result of a robbery.
The investigation is ongoing.
Anyone with information is asked to contact police at 1-800-577-TIPS.