Police, ambulance attend three serious crashes in Perth, Welshpool and Bentley

IT has been a horror afternoon on the roads in Perth, with three serious crashes taking place in less than an hour across the metro area.

A serious crash involving a car and a pedestrian shut down William Street northbound in the Perth CBD just after 3pm.

A St John Ambulance WA spokeswoman said paramedics had transported a man in his late 20s, believed to have serious injuries, to Royal Perth Hospital

Police were also on the scene and the northbound lane had been closed near Mounts Bay Road.

That section of William Street has now been reopened.

Police and paramedics are also at the scene of another serious crash involving a car and a motorcycle in Welshpool.

A St John Ambulance WA spokesman said the motorcyclist, a man in his 40s, was transported to Royal Perth Hospital.

A second ambulance crew was on the scene to assist. The driver of the car is understood to have only suffered minor injuries.

The crash has shut down Orrong Road eastbound from Kewdale Road to McDowell Street.

Drivers should avoid the area.

A third serious crash was reported in Bentley, near the intersection of Manning Road and Centenary Avenue.

Police and two St John Ambulance crews were sent to the scene of a two-car crash.

A St John Ambulance spokesman said no patients were transported from the scene.

The crash has since been cleared and traffic is flowing normally in the area.