At about 9pm on Wednesday, a female employee was preparing to close at a restaurant on the Pacific Highway when a teenage girl entered the store and allegedly threatened her with a broken bottle.

The worker ran out of the store and alert another staff member in the carpark who notified police.

Police said the girl fled the store with cash and the employee's mobile phone.

Officers attached to Lake Macquarie Police District attended and conducted extensive patrols of the nearby area.

A crime scene was established and forensically examined.

At about 11.30pm, police spoke with a teenage girl leaving another fast food store on the Pacific Highway, Charlestown.

During a search, police allegedly located the employee's mobile phone and a sum of cash in her possession.

The 15-year-old girl was arrested and taken to Belmont Police Station.

She was charged with armed robbery and refused bail to face a children's court on Thursday, November 28.