The robbery took place at 2.15pm on Friday 15 November at the store on Bong Bong Street.
An armed man entered the premises and threatened a 70-year-old female staff member with a firearm, demanding cash.
A 75-year-old man, who had been working in a back room, responded to the commotion and was injured as the armed man smashed a cabinet and stole items of jewellery.
The robber then fled the scene in a car, which police believe to have been stolen.
NSW Ambulance paramedics later treated the 75-year-old man for minor injuries and Hume Police District officers established a crime scene.
The suspect remains at large.
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