Update 1.15pm: The crash site has been cleared and traffic flow has returned to normal.
Earlier: A car has overturned on the M1 Princes Motorway at Kanahooka.
NSW Ambulance paramedics were called about 12.35am and are now assessing three people who are believed to have suffered minor injuries.
The car came unstuck in a northbound lane underneath the Kanahooka Road overpass.
Emergency services are at the scene.
The crash is interrupting the flow of northbound traffic. As at 1.10pm, the queue stretched for 1km.
Motorists are advised to avoid the area if possible.