Just after midnight, two men entered the service station on Sir Donald Bradman Drive and threatened staff, while demanding money. One of the men was armed with a knife.
An amount of cash was stolen, along with cigarettes, and the two men then ran away towards Adelaide.
No one was injured during the incident.
The first suspect was wearing a long-sleeve camouflage jacket with a hood, black jeans and black sneakers. He was also carrying a black backpack with white writing on it.
The second suspect was wearing a black jumper with a camouflage-pattern hood, black jeans, black sneakers and white gloves.