Police are investigating the circumstances surrounding an armed robbery at a service station in Colyton overnight.

About 10.45pm (Monday 2 November 2015), two men entered a service station on The Great Western Highway and produced a firearm.

They threatened a male employee and demanded cash from the register and cigarettes.

The employee handed an amount of cash and a small amount of cigarettes before the pair ran from the store.

Police were called and a crime scene was established while specialist police conduct further inquiries.

Anyone who may be able to assist detectives with information concerning this robbery should call St Marys detectives.