Main Roads has also closed South Western Highway northbound, south of Boyanup.
A man in his 20s is being rushed to Royal Perth Hospital by the RAC rescue helicopter after being hit by a truck.
Around 7:30 this morning the truck struck a pedestrian at the South Western Highway and Shenton Road intersection in Boyanup.
The victim sustained head and back injuries in the crash.
Police remain on site with traffic management in place.
Main Roads advises motorist to seek an alternate route.
Concerns for missing man last seen in Medina
Rockingham Police are asking for the public's help to find a missing 47-year-old man.
Man charged after slashing victim's neck with glass in Madora Bay
A 37-year-old man has been charged after allegedly slashing another man's neck with a piece of glass in Madora Bay.
Rockingham disability accommodation and social housing refurbished thanks to State Government grant
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Local fishers asked to have their say on extending crabbing season closure, simplifying bag and boat limit rules
Public consultation is now open on proposed changes to blue swimmer crab rules in the West Coast bioregion including Mandurah.
Detectives hunt driver who reversed into Mandurah tobacco store
Detectives are on the hunt for a driver who reversed into a Mandurah tobacco store.
Mandurah Crab Fest boasts huge range of free, family friendly entertainment
The Channel 7 Mandurah Crab Fest is set to dish up a huge range of free, family friendly entertainment and activities this weekend (March 14 and 15).
Fuel prices surge in Perth, Mandurah
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Teen boys charged over Mandurah burglaries
Two teenage boys have been charged following an investigation into a series of alleged burglaries in the Mandurah area.
Tragic update in search for missing man Robert Snyder
Police have confirmed they have located a body believed to be missing man Robert John Snyder.