Police are investigating the armed robbery of a petrol station at Blacktown last night.

About 8:45pm, Sunday 12 May 2013, two men wearing hoods over their heads, entered the petrol station on Richmond Road.

One of the men threatened the console operator with a knife while the other jumped through the security wires of the counter and demanded money from the til.

He was handed a small sum of cash before both men ran out of the store.

The pair was seen running through the car park and across the road into Wright Street where they fled in a Black Holden Commodore which was last seen travelling west along Richmond Road.

Police were called to the petrol station and established a crime scene which was examined by officers from the Forensic Armed Robbery Unit.

Detectives from Blacktown are now investigating the robbery and are looking for the men who have been described as being of Pacific Islander/Maori appearance, aged in their early 20s with medium builds.

One of the men is described as being 168cm tall and wearing a red hooded jumper and black track pants while the other is described as being 183cm tall and wearing a grey hooded jumper and black shorts.