The main state highway north and south of Auckland is beginning to clog with holiday weekend traffic, while motorists also face an hour's delay further north after a fatal crash.
One person is dead and a man in his 20s is in a critical condition after two cars collided head on north of Auckland.
State Highway 1 is closed after the crash, near Te Hana. It remained closed this afternoon, with drivers sent on an hour-long detour through Mangawhai.
Area Commander of Waitemata North Inspector Bruce O'Brien said two vehicles crashed north of Wellsford at around 11.15am and the driver of one of the vehicles died at the scene.
The driver of the other vehicle was airlifted to Auckland Hospital in a critical condition.
Auckland Rescue Helicopter Trust intensive care paramedic Russell Clarke said it was high-speed and high-impact crash that happened on a slippery blind bend.
"It took us about 40 minutes to get the guy in critical condition out of the car. We had to cut open the roof and remove the steering," Clarke said
O'Brien said the Serious Crash Unit and other emergency services were still dealing with a large scene which was expected to take some time to clear.
SH1 TE HANA - ROAD CLOSED - 2PM UPDATE SH1 remains closed just north of Te Hana (Mangawhai Rd) through to Kaiwaka, ALL roadworks on Mangawhai Rd have been picked up to help ease traffic congestion along the detour route. ^MF https://t.co/cVIOh4zmCd
— Waka Kotahi NZTA Auckland & Northland (@WakaKotahiAkNth) June 1, 2018
"There are diversions in place but with heavy traffic expected due to it being a long weekend, we ask motorists to either avoid the area or please be patient.
"This is an absolutely tragic way to begin the long weekend and we please ask that everyone takes extreme care when out on our roads this weekend."
Four fire engines also attended the incident.
NZ Transport Agency said the crash was blocking SH1 north of Te Hana. The road is closed and diversions are in place at Mangawhai and Kaiwaka-Mangawhai Rds.
It is asking motorists to avoid the area or expect delays and diversions.
The road closure is likely to cause havoc to motorists trying to leave the city for the long weekend.
UPDATE 11:50AM#SH1 is NOW CLOSED north of Te Hana thru to Kaiwaka, with detour in place via Mangawhai. Allow extra 25-30 mins for detour. ^TP https://t.co/cVIOh4zmCd
— Waka Kotahi NZTA Auckland & Northland (@WakaKotahiAkNth) May 31, 2018
Five people have been left with injuries after a crash between a car and a truck north of Balclutha.
A police media spokeswoman said the crash happened about 10.20am.
One lane of State Highway 1 was blocked and police, fire and ambulance crews were on the scene.
One person had been trapped in a vehicle for a time.