Kwinana Freeway northbound has been shut down during peak hour on the first day back from the Easter Holidays due to a crash.

The freeway has been closed at Mundijong Road, with Main Roads telling drivers to consider using Baldivis Road as an alternative.

Commuter James called in to Millsy and Karl on 6PR Breakfast to say RAC Rescue helicopters have landed near the accident.

Police say a man in his 50s has been flown to Royal Perth Hospital, while a woman in her 30s has already been taken to Fiona Stanley Hospital by ambulance.

Press PLAY to hear more about the crash

Image: Main Roads WA