Traffic is still crawling northbound between Plimmerton and Paraparaumu, near Wellington, more than two hours after two crashes and a diesel spill on State Highway 1 caused chaos for emergency services.
Police asked motorists to be patient, "drive with extreme caution", reduce their speeds and avoid non-urgent travel.
One motorist told NZME he and his wife had been stuck in traffic for about an hour on their way home from dinner in town.
Five people were hurt, one seriously, when a car and truck collided just north of the Paekakariki railway crossing about 6pm.
The seriously injured person was airlifted to hospital and the other four were taken to hospital by ambulance in a moderate condition, police said.
