POLICE are seeking witnesses to a serious crash in Alexander Heights yesterday.
About 6.15pm, a 16-year-old boy was riding an unregistered off-road motorcycle west along Marangaroo Drive.
The boy was riding with two others with similar motorcycles when he crashed into the rear of a Ford Territory travelling in the same direction.
The car stopped at the scene and the other two motorcycles rode off, west along Marangaroo Drive.
The boy received serious head injuries and was taken to Royal Perth Hospital.
Call Crime Stoppers on 1800 333 000 or go to www.crimestopperswa.com.au.