Three people have died after a crash at Gidgegannup, 40 kilometres east of Perth.
Police say a truck and a four-wheel-drive collided on Toodyay Road near the Noble Falls Tavern just before 9:00 am. (WST)
Police have confirmed a 28-year-old woman and her two sons, aged three and six, were killed in the crash.
Inspector Dominic Wood says it is a horrific scene.
"The three people that have died this morning were in a passenger vehicle that has collided with a heavy truck," he said.
"The driver of the truck is physically ok but obviously will be suffering some emotional stress, I imagine.
"It's a shocking scene for officers of DFES and ambulance crew."
Inspector Wood says the crash will also affect the community.
"This is a tragedy not only for the family involved in this crash, it's a tragedy for the local community, it's a small community up here," he said.
He is appealing for witnesses to come forward.
"There are some witnesses that we are speaking to at the moment and we ask anybody that has witnessed this or may have witnessed the vehicles travelling before the crash has occurred, to please come forward and talk to us."
Inspector Wood says it may be some time before police can piece together what happened.
"We're investigating it thoroughly," he said.
"Major Crash have arrived at the scene, they're currently conducting their investigation, we're a long way off from knowing exactly what's happened, it's too early to say."
The road is blocked and motorists are being advised to avoid the area until further notice.