A South Side Jack in the Box was robbed at gunpoint after an employee left the back door open while taking out the trash.
Police said the robbery happened around 10 p.m. Tuesday in the 500 block of Fair Avenue.
The suspect, a man in his 20s, went into the restaurant and headed straight towards the manager's office in the back of the building.
The suspect pointed a gun at the manager and demanded money, police said.
The suspect fled with an undisclosed amount of cash. Police have a description but have not announced an arrest. No injuries were reported.