About 4.15pm, an eight-year-old boy was riding a scooter south along Harold Road.
As he crossed the road, he collided with a Jeep Cherokee travelling west.
He received serious injuries and was taken to St John of God Midland Public Hospital before being transferred to Princess Margaret Hospital.
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READ NOWAnyone who saw the crash, the boy on his scooter or the Jeep Cherokee prior to the crash, is asked to call Crime Stoppers on 1800 333 000 or report the information online at www.crime|stopperswa.com.au.
Police are seeking assistance from two women described as dark skinned, 30-40 years of age, one with light brown hair, large build, wearing a black jumper (Adidas logo) and the other with dark brown hair, wearing an orange jacket, black jumper (Puma logo), black pants and white sneakers. Anyone with information can call Perth Police Station on 9422 7111 or Crime Stoppers on 1800 333 000 with reference 310716 1800 88775.