Police say they arrested a 33-year-old Palmerston man after the incident, and he will appear in court on Monday.

"Around 11.05am the man entered the Civic Video Gungahlin store and threatened a staff member with an object wrapped in a plastic bag, claimed to be handgun, demanding cash. The staff member complied, handing over a sum of cash," police said in a statement.

"Police attended shortly after and reviewed CCTV footage of the area. Based on information gathered, police arrested a man in Palmerston before executing a search warrant on a nearby house in Kosciuszko Avenue where police seized items in relation to the offence."

The Palmerston man has been charged with aggravated robbery and possession of a prohibited substance. He was remanded in custody.