Police are on the tail of a silver Holden Cruze sedan, registration '1DJL 456' with a black bonnet and boot - last seen in Dorothy Street, Gosnells.
The occupant/s of the car are armed with a firearm, and it is believed the firearm has been set off at least once.
Members of the public are advised not to approach the vehicle.
Police chase gunman last seen in Gosnells
Police chase gunman last seen in Gosnells
Anyone who sees the vehicle is asked to call 000 immediately and report the location.