A truck has rolled on State Highway 1 near the entrance to Auckland Victoria Park tunnel blocking all three northbound lanes of the motorway.
The NZ Transport Agency says the crash happened just before 1pm.
The NZTA says it will take some time to remove the truck and re-open the motorway. It says there will be widespread congestion.
The motorway north is closed from the nelson Street off-ramp.
The NZTA advises northbound drivers to leave SH1 as soon as it is safe for them to do so and use alternative routes. They can rejoin the motorway at Fanshawe Street in the CBD, but the NZTA says quicker alternatives will be the Southwestern Motorway (SH20) at Manukau or the Northwestern Motorway (SH16) as an alternative.