A 28-year-old Bayswater woman has serious injuries after a man threw a rock at her convertible car's windscreen, sending the vehicle off the road and into a power pole.
The woman was driving her Mazda MX-5 south on Garratt Road, Bayswater, about 7.20pm on Wednesday when, about 300m before the bridge, a big rock was thrown at her windscreen.
She veered and crashed into a power pole and the car rolled.
The car's top was down.
It is understood a passerby helped the woman from the wreckage.
She is in Royal Perth Hospital with serious head injuries. Police say she is incredibly lucky to be alive.
They believe a dark-skinned man with a medium build seen near the crash threw the rock from the roadside.
The seriousness of the woman's injuries and the possible intent of the rock thrower has led Mirrabooka detectives to take charge of the investigation.
Det-Sgt Steve Da Re said police were committed to stamping out antisocial behaviour in the area.
"This is a tragic situation," he said. "These things should not be happening in the public today and any members of the public who saw something like this, please contact police."
Det-Sgt Da Re confirmed police were investigating reports of antisocial behaviour, including glass bottles being thrown, before Wednesday's attack.
Police are also investigating a serious motorcycle crash that left a 25-year-old man fighting for his life.
The man was riding north on Alexander Drive, Menora, about 4.45pm on Wednesday when he failed to negotiate a bend and his bike mounted the verge and hit a tree.
The man was pinned under a parked car.
He is in a critical condition in the intensive care unit at Royal Perth Hospital.
Ambulance workers were kept busy on Wednesday night when eight people were injured when a Toyota Camry and a Nissan Pajero collided at Durban and Leake streets in Belmont about 10pm.
The impact forced the Pajero into the front yard of Chris Thompson's property.
Mr Thompson said the intersection was so dangerous he would not sleep in his front room for fear of having a car plough through and kill him.
Last night, the road toll for the year was 31, compared with 18 at the same time last year.
Anyone with information on the crashes is asked to call Crime Stoppers on 1800 333 000.