Police are looked for a man armed with a pistol who held up the Caltex Service Station on the Main South Road at Hornby, early on Sunday June 9.
He entered the service station at 5.45am with a red scarf over his face and wearing a black hooded sweatshirt, black pants, and carrying a pistol.
The offender, described as skinny, demanded cigarettes and cash before running off towards Goulding Avenue.
A police dog tracked him before losing the trail in the Kyle Park area.
Detectives and forensic staff have been conducting a scene examination and police say there is clear security camera footage of the offender from the service station.