WorkSafe is investigating the work-related death of a 45-year-old man at a plant hire business in Baldivis on Saturday morning.
The man was believed to have been performing mechanical repairs on a truck when he was struck by part of the truck.
Inspectors travelled to the site soon after and will interview witnesses and investigate the circumstances.
WorkSafe thoroughly investigates serious work-related injuries and deaths in WA with a view to preventing future incidents of a similar nature.
WorkSafe WA Commissioner Nina Lyhne said any work-related death was a tragedy, and relayed her sincere condolences to the man's family.