An elderly driver and her passenger were travelling west on the highway when their vehicle and another car collided on Tuesday afternoon.

The second car contained a family, including three children.

The father was taken to Stawell Hospital with chest injuries.

Others were treated at the scene for minor injuries. 

Acting Sergeant Scott McKenzie said fatigue might have been a factor in the crash.

He said it appeared the elderly driver drifted into the middle of the highway. 

Acting Sgt McKenzie urged people to be cautious travelling long distances and in inclement weather.

The highway was closed for about 45 minutes while emergency services attended.