Investigators believe a B-double truck travelling west on the Western Highway at the Black Range and an east-bound semi-trailer collided head-on about 11.30pm on Wednesday.

Two bodies were among the wreckage.

Stawell truck crash: Police urge people to call employers first

The driver of a third vehicle, a man in his 50s, was critically injured after his semi-trailer crashed into the rear of the other semi-trailer.

All three trucks were engulfed in flames.

Ambulance Victoria spokesman John Mullen said the survivor had significant, full-thickness burns to most of his body.

“He also had burns to his airways, and fractures,” he said.

Paramedics treated the man at the scene before taking him to Stawell Hospital.

He was further stabilised there, in preparation for a flight to Melbourne.

“He was flown to The Alfred in a critical condition,” Mr Mullen said.

Hospital spokeswoman Hannah Chipp said the man’s condition had been downgraded to ‘serious but stable’ by 1.45pm.

While she said it was a promising sign, she stressed the man was still seriously ill.

The Western Highway remained closed late Thursday as investigations continued.

The State Coroner, Victoria Police disaster victim identification specialists and accident investigators worked to identify the two dead people.

Police media officer Natalie Webster said the families of those involved would be informed as soon as the process was complete.

She said police had received many calls from people concerned about family members who were truck drivers, who might have been in the area on Wednesday night.

“We ask people concerned about their family members who are truck drivers to call trucking companies or employers in the first instance,” she said.

“Any trucking companies with queries should call Ararat Police Station on 5355 1500.

"Police ask that only trucking companies call police.”

VicRoads western regional director Ewen Nevett said staff inspected the crash site on Thursday afternoon.

He said the road surface and safety barriers seemed to have been damaged.

“Further inspections will be done after debris has been cleared,” he said.

VicRoads will resurface the road as soon as possible.

Mr Nevett said Western Highway duplication to Stawell would be completed in stages, subject to future funding.

He said the state and federal governments had also committed $48.45 million to improve the highway between Stawell and the South Australian border.