Police have been told the armed man demanded money and threatened the employee, before the employee retreated into a back area of the premises.
The armed man unsuccessfully attempted to gain access to the back of the counter, before forcing the doors to the service station open and fleeing the scene.
The employee was uninjured.
Police have released CCTV footage of a man who may be able to assist with inquiries.
The man is depicted in the footage as wearing a dark long-sleeved top with a white emblem on the left chest area, a black cap, khaki knee-length shorts and black running shoes.
Anyone with information or dashcam footage is urged to contact Auburn Detectives or Crime Stoppers on 1800 333 000.