Major Collision Investigation Unit detectives are investigating after two people were killed in a crash in Laharum this afternoon.
A semi-trailer crashed into the rear of a car turning into a rest stop on the Western Highway about 12.20pm.
The car has been pushed into oncoming traffic, colliding head-on with another vehicle.
The female drivers of both vehicles died at the scene.
A male passenger in one of the vehicles sustained life-threatening injuries and will be airlifted to hospital.
The uninjured male truck driver was arrested and is assisting police with their enquiries.
The Western Highway is expected to be closed for most of today while detectives examine the crash scene.
Anyone who witnessed the crash, has dash cam footage or any information that could assist investigators is urged to contact Crime Stoppers on 1800 333 000 or submit a report online at www.crimestoppersvic.com.au.