Police are investigating after a shot was fired during an armed robbery in Sydney’s west this evening.

About 6.30pm (Friday 8 June 2018), police were called to a service station on Boundary Road, Chester Hill, after an unknown man threatened a staff member with a firearm and demanded cash.

A shot was fired during the incident; however, no one was injured.

The man left the area and was last seen heading north on Furndell Street.

He is described as being of Pacific Islander/Maori appearance with a large build.

He was wearing dark-coloured clothing and had his face covered.

Officers from Cumberland Police Area Command attended and conducted a search of the area; however, the man was not located.

A crime scene has been established and an investigation has been launched into the circumstances surrounding the incident.

Anyone with information is urged to contact police immediately.