A woman has been cut free and a man has been arrested.
The crash has since been cleared.
More information to come.
Emergency services are at the scene of a serious multi-vehicle crash in Mandurah on Friday.
St John Ambulance, firefighters and police were called to the intersection of Pinjarra Road and Leslie Street after reports of a traffic collision about 3:45pm.
Firefighters from Mandurah and Falcon along with paramedics worked to free a driver who was trapped in one of the vehicles.
Traffic was heavy in the area as Pinjarra Road was closed in both directions at Leslie Street.
Drivers heading east, into Mandurah over the bridge, were diverted along Mandurah Terrace.