A male and female, aged in their late 60s and early 70s, died at the scene after their late-model Hyundai sedan and a four-wheel-drive ute collided on the Hamilton Highway just after 11.30am.

The driver of the twin-cab ute, aged in his 70s, was flown to Melbourne’s The Alfred hospital with serious chest injuries and remains in a critical condition in a Melbourne hospital. 

A spokesman for The Alfred hospital this morning said the man was listed as being in a "critical but stable condition". 

An Ambulance Victoria spokesman said crews worked to free the man from his vehicle for about an hour as temperatures soared to 41 degrees. 

The spokesman said paramedics then worked to stabilise the man before he was flown out by helicopter just before 2pm. The two people killed had to be cut free from the wreckage of their severely damaged sedan.

The smash happened on a straight stretch of the Hamilton Highway about eight kilometres east of Lismore. 

There were no skid marks and very little debris around the accident scene.

The highway was closed in both directions until late yesterday afternoon as investigations continued.

Warrnambool police inspector Kevin Archer said early investigations suggested one vehicle had moved on to the wrong side of the road.

“We believe the sedan was headed east towards Geelong and the ute was headed west towards Lismore,” Inspector Archer said.

“At this stage it isn’t exactly clear what’s happened, our investigations will continue. In this case it looks like one car has veered into the path of another. 

‘‘We don’t know what’s caused that but it’s a good reminder not to drive when you’re tired and fatigued.”

Inspector Archer said it was a tragedy in the lead-up to the busy Christmas holiday season.

“As we head into the busy summer holiday period, there will be increased traffic on the road. 

‘‘We need all drivers to stay alert and take care.

“We want to make sure everyone gets to their destination safely.”

Police units from Warrnambool, Cobden, Skipton, Lismore, Camperdown and Mortlake were assisted at the scene by local CFA and SES crews.

The deaths bring Victoria’s road toll to 235 compared with 272 at the same time last year.