The Major Collision Investigation Unit is examining a fatal crash that occurred in Mount Moriac this morning.

Preliminary reports indicate a Mazda CX-5 and a Toyota Landcruiser collided near the intersection of Cape Otway Road and the Princes Highway around 11:30 a.m.

A male passenger in the Mazda, who has not yet been formally identified, tragically died at the scene. A female passenger of the Mazda was airlifted to hospital with serious injuries.

The driver and a fourth passenger of the Mazda, along with the sole occupant of the Toyota Landcruiser, were transported to the hospital with non-life-threatening injuries.

The female driver of the Mazda is currently under police guard.

Investigators are still working to determine the exact circumstances of the collision. The road is expected to remain closed for an extended period as detectives process the scene.

Police are urging anyone who witnessed the collision or has dashcam footage to contact Crime Stoppers at 1800 333 000 or submit a confidential report online at www.crimestoppersvic.com.au.