Westgate Highway Patrol members are investigating following a two-vehicle collision in Truganina on Wednesday afternoon.
It is believed a black Ford Territory collided with a Country Fire Authority truck on Forsyth Road, at the intersection of Elmhurst Road, about 6pm. The CFA truck was attending a grass and scrub fire in the area at the time.
The driver of the Ford, along with three child passengers, sustained minor injuries and were transported to hospital.
Two occupants of the truck were uninjured.
Police are investigating the cause of the collision and urge anyone with dashcam footage of the incident to come forward.
The grass and scrub fire the CFA were attending.
The CFA is aware that one of its tankers from Diggers Rest was involved in the collision and will be assisting police with the investigation into the cause.