Police are investigating an armed robbery which occurred at a shopping centre in Sydney’s west.

About 11.40am yesterday (Sunday 6 December 2015), a 15-year-old boy was working at a retail store in the shopping centre on Main Street, Blacktown, when a male approached him at the register.

The man removed what is believed to be a firearm from a plastic bag and pointed it at the boy. He demanded money and was handed an amount of cash.

The man then fled the store and left the shopping centre. He was last seen heading in the direction of the railway station. The boy was uninjured.

The offender has been described as 50-60 years old, with long brown hair in a ponytail, and wearing a black cap, a black shirt with a white motif, black knee length shorts, and thongs.

He had tattoos on both lower arms and was carrying a grey plastic bag with what is believed to be a firearm in it, which was covered by a cloth.