According to investigators, a middle-aged white man with a salt-and-pepper beard entered the Fifth Third Bank inside a Kroger grocery store off Roswell Road at about 6:30 p.m.
He told the teller he had a handgun and demanded money, police say.
After receiving an undisclosed sum of cash, the suspect fled the bank on foot, when investigators say he was last seen running east through the parking lot.
Although the suspect stated he had a handgun, police say he never displayed one.
Investigators are asking anyone with information about the robbery to call (770) 499-3945.