A pedestrian has been struck and seriously injured by an object that fell from a passing vehicle.

A white Toyota Hilux utility was towing a trailer when the load it was carrying dislodged and hit a 53-year-old woman, WA Police said.

The emergency happened on Third Ave in Kelmscott, in Perth’s southeast, about 2.35pm on Wednesday.

The woman was taken to Royal Perth Hospital with serious injuries.

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The Hilux driver, 25, is assisting the Major Crash unit, which has launched an investigation.

Anyone with information should contact Crime Stoppers.