The rescue helicopter has been sent to a motorcycle crash on the Kwinana Freeway in Stake Hill.
The crash happened near the Lakes Road turnoff just after 11am on Monday.
Emergency crews are at the scene.
Police believe the rider has suffered serious injuries.
The Kwinana Freeway is closed southbound at Mandjoogoordap Drive.
Kwinana Fwy CLOSED southbound at Mandjoogoordap Dr to Lakes Road, Stake Hill due to a serious crash AVOID THE AREA more info: https://t.co/EmkqlV8vZ1 #perthtraffic
— Main Roads WA (@Perth_Traffic) December 3, 2018
City of Kwinana proposes 4.5 per cent rate rise
Recreational boat fishers offered $50 rebate for fishing gear at participating tackle shops
Waikiki teen among the best CrossFit athletes in the world
Mandurah's Kerrie Overell crowned WA Volunteer of the Year
Wellard home destroyed by fire
Woman fined $7k after catching 134 undersize crabs in Coodanup
Mandurah mayor Amber Kearns 'disappointed' in councillor Peter Rogers' decision to resign
Speed limit dropped to 70km/h on stretch of Mandurah Road in Secret Harbour
WA Police officer tragically dies in hospital days after Hopeland crash