A truck has hit and killed two pedestrians on Brookton Highway in Jelcobine, south-east of Perth.
Police said the man and woman were walking on or adjacent to the highway about 12:30am when they were struck.
They both died at the scene.
It is understood the driver of the truck was uninjured in the crash.
Brookton Highway remains closed in both directions between Westdale Road and York-Williams Road.
The crash happened about 100 kilometres from Perth.
Police Major Crash investigators remain at the scene.
"Sadly, both a male and a young woman have lost their lives, it's a tragedy that Major Crash together with local police are investigating," Police Commissioner Chris Dawson said.
"If anyone saw people walking on Brookton Highway near Brookton early this morning, please come forward and notify us.
"Or if you've got any dash [cam] vision if you've been travelling on the Brookton Highway in the early hours of this morning, again we'd ask you to come forward.
"The loss of two people's lives on a highway at night in the country is a real tragedy for those families."
