Major crash investigators will travel to Glen Iris today following the death of a five-year-old Bunbury boy in hospital overnight.

The boy was riding his bike along Woodley Road near the entrance of Gidgee Entrance about 6.30pm when he was hit by Mitsubishi Pajero.

Police yesterday said the driver of the Pajero did not see the boy on his bike before the crash.

The boy was taken to Bunbury Hospital and later flown to Princess Margaret Hospital with suspected head injuries.

He died overnight.

Anyone with information is asked to call Crime Stoppers on 1800 333 000.