A 12-year-old boy hit by a truck while riding his bike in Butler has died in hospital.

The boy, who had been riding without a helmet, reportedly underwent brain surgery in Royal Perth Hospital early on Friday after being transferred from Joondalup Health Campus, where he was taken following the incident on Thursday afternoon.

He later died.

A St John Ambulance spokesman said paramedics called to the accident scene just after 2.30pm on Thursday found the boy with "multiple serious injuries, possible fractures, cuts and abrasions".

The crash occurred on the corner of Swavesey and Connolly Drive, Butler.

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