Motorists were advised to avoid the motorway at this time, or delay travel.
NZ Transport Agency Waka Kotahi (NZTA) advised people to pass with care and expect delays.
Two of the three eastbound lanes are blocked after the Lincoln Rd on-ramp, it said.
Traffic on the Northwestern Motorway. Photo / Google Maps
Google Maps showed gridlocked traffic on the motorway for 4km from the Lincoln Rd on-ramp back to the Hobsonville Rd on-ramp.