Rijksweg 1 near Waipu remains blocked for several hours after a collision with a truck and a car.
The crash happened shortly after 6.30 am on the Brynderwyn Hills, the police said.
At 8:00 am the police said that the road would remain closed while heavy towing equipment was brought in to remove the vehicles.
"Two people had minor injuries and were taken to Whangarei Hospital for use
Motorists are asked to avoid the area and take alternative routes.
Diversions were in place south of Whangarei, via Mangapai and Paparoa, before returning to SH1.
Fire and Distress New Zealand is present at the crash. The crew also offers traffic assistance.
Meanwhile, traffic on the southern highway of Auckland is growing after a crash and a breakdown.
While the slump on the shoulder of the Greenlane exit does not block lanes, the traffic is already heavy because of a crash just before the Panama Rd exit between Drury and Takanini.
The crash caused delays to Highbrook and congestion to Mt Wellington.
The rest of the highway is free flowing, but traffic is heavy on the northwestern highway via Royal Rd and slowly between Western Springs and The Northern Link.
The Northern Motorway is sometimes heavy for those who move into the city between McClymonts Rd and Tristram Ave.
A crash has crashed in Wellington, which has blocked part of Rijksweg 1 to the north from the capital.
SH1 has been reopened for those who drive north from Wellington.
The highway was blocked for about an hour this morning after the crash at Johnsonville.
Motorists are told to expect delays when congestion clears up.
The crash happened on the motorway just after the Johnsonville exit around 6 o'clock this morning.
The road is the main highway from Wellington.