Stoneleigh highway horror: Two adults and a toddler are killed after their car was crushed by a truck on a busy motorway

Three members of family, including a toddler, have been killed after a car and a B-double truck collided on a major motorway.

Emergency services rushed to the intersection of Eurambeen-Streatham and Mount William roads in Stoneleigh, 200km from Melbourne, about 9.30am on Tuesday.

Victoria Police said a car carrying three generations of the same family allegedly drove through a stop sign and collided with the truck.

The driver, a 41-year-old man, a 31-year-old female passenger and a three-year-old boy died at the scene.

Another woman, who was trapped in the rear passenger seat, suffered life-threatening injuries and was airlifted to the Alfred Hospital.

The truck driver is understood to have sustained minor injuries and was taken to Ballarat Base Hospital in a stable condition.

Detective Inspector Craig McEvoy said the driver, a local man, is cooperating.

'The truck driver is shaken as you'd expect, he's with family and friends,' he said.

'It's a terrible scene.'

Det Insp McEvoy said the bodies of the deceased were not removed from the scene until 3pm due to their significant injuries.

Witnesses or those with dashcam footage have been urged to contact Crime Stoppers.

According to data from Victoria Police, 247 lives have been lost on roads so far this year, including 18 children.

Last year, 241 people died on Victorian roads up to November.

Stoneleigh, which is about 45 minutes from Ballarat, is a small town with a population of 45 people.