A young boy is dead after a trailer of fertiliser collapsed on top of him in regional Victoria.

A family member was driving a tractor spreading fertiliser at a farm in Naringal, near Warrnambool, about 11am on Wednesday when the trailer collapsed.

“The family member had been manoeuvring the spreader off or on the tractor and it has collapsed onto the two-year-old child, who is a few months shy of his third birthday,” Sergeant Matthew Laxton told AAP.

“It just appears to be a legitimately terrible accident.”

The family member had not been aware the child was in the area or injured but as soon as they were, they went to his aid.

Family and farm staff tried to help the toddler before road and air ambulances arrived but the boy could not be saved.

“It is a family-run farm so many family members were present at the time,” Sgt Laxton added.

“The family are fairly distressed but they are being well supported by the local community.”

Police and WorkSafe are investigating the circumstances of the death.