A toddler is dead and three others are fighting for life after a shocking smash on the Calder Freeway.

The tragic incident involving multiple vehicles happened at Diggers Rest on Monday afternoon.

Victoria Police said it was believed a truck carrying grain collided with a number of vehicles near the Bulla Road overpass about 2.30pm.

A toddler in the back seat of a car carrying four people died at the scene.

A one-year-old girl and a 37-year-old woman remain in critical conditions in hospital, and a 35-year-old man who was in the same car is in a stable condition.

A man in another vehicle who became trapped under the truck is also in a critical condition.

The male driver of the truck has been released from police custody pending further enquiries.

Anyone who witnessed the collision, dashcam footage or further information is urged to contact Crime Stoppers on 1800 333 000 or submit a report online at www.crimestoppersvic.com.au.

“It looks horrendous,” caller Mark told 3AW Drive from the scene.

Press PLAY below to hear Mark’s call to 3AW

Picture: 9 News