Two males, believed to be teenagers, were confronted by a staff member at The Warehouse in Hillside Rd after being caught shoplifting about 2.30pm, Sergeant Jared Kirk said.
"One of them made a couple of comments to suggest they were carrying a firearm,'' he said.
"He then lifted his singlet to show something that looked like a handgun.''
The staff member attempted to get the shoplifter to come upstairs to a secure area, but he and his associate fled the scene, Sgt Kirk said.
The pair did not make any overt threats about using the weapon or harming anyone, he said.
"It looks like they are probably youth offenders.''
Considering the age of the pair and the description of the weapon it was "probably unlikely'' it was a genuine firearm, but police were keeping an open mind.
"We don't really know and we have got to be careful about how we approach these sorts of jobs,'' he said.
A visibly shaken Warehouse staff member was seen talking to police shortly after the incident.
Senior Sergeant Stephen Larking last night said police had not apprehended anyone related to the incident, but were following a positive line of inquiry.
Police had CCTV footage of the youths, but would not release the footage or a description of the suspects.
"Inquiries are continuing,'' Snr Sgt Larking said.
