UPDATE: A man has died after his truck rolled near New Norcia about 12.45pm.
The crash happened on the Great Northern Highway near the Calingiri-New Norcia Road.
The tragedy follows the death of an 85-year-old woman who died yesterday after driving into the path of another vehicle at Coolup, 95km south of Perth.
Police say the woman was driving a Toyota Corolla about 4.30pm on Saturday and stopped at the intersection of Gibbins and Maryfield roads.
It is understood that she then drove into the path of a Landcruiser driven by a probationary driver, who was unable to avoid the collision.
Firefighters attempted to free the woman who was trapped in the vehicle, but police say she died at the scene.
Two hours earlier, in Durack in the State's far north, a 32-year-old man from Halls Creek was killed when his Honda station wagon rolled over on the Great Northern Highway, near McPhee Creek.
Motorists are reminded that double demerit points will remain in place today as the holiday period comes to an end.
Police are urging WA drivers to be aware of signs of fatigue and to remember to wear a seat belt.
"With a little care and attention by everybody, death and serious injury on our roads is entirely preventable," Road Safety Council's Professor Murray Lampard said.
"At all times drive to the conditions and adhere to the posted speed limit."