Two males armed with a sledgehammer and knife broke into a Moolap service station to steal cash and cigarettes just before peak hour on Tuesday.
The two masked men entered the Portarlington Rd service station about 4pm, police alleged.
The store attendant managed to lock himself in an office and was unharmed.
The offenders stole cash and cigarettes from the premises before fleeing in a vehicle, police alleged.
Police believed that vehicle to be a grey Holden Commodore.
They described the first male as having a solid build and said he was wearing a grey hoodie, grey pants and brown boots at the time of the robbery.
The second male had a solid build and was wearing a black hoodie, dark pants and black runners.
Police later spotted the alleged getaway car traveling north along the Western Ring Rd and initiated a short pursuit before terminated it for safety reasons.
The car was last seen travelling between Fitzgerald Rd and Ballarat Rd.
Police continued their investigation on Wednesday morning.
They urged anyone with information to phone Crime Stoppers on 1800 333 000 or make a confidential online report at www.crimestoppers.com.au.
