The police serious crash unit, a police photographer, firefighters and ambulance services were called to the scene.
The deaths have been referred to the coroner.
Police said no details would be released until they had been formally identified and next of kin had been informed.
Police closed the motorway while the serious crash unit completed its scene examination.
It was expected to reopen about 10pm.
Last night, a fiery crash between a car and a minivan in the Bay of Plenty claimed three lives and left seven others injured.
The vehicles collided on State Highway 2 in Te Puna and burst into flames about 7.30pm.
Those killed were all women from the same extended family in Auckland, aged 71, 45 and 32. Their names were yet to be released by police.Emergency services were called to the Northern Motorway, near the Main North Rd off-ramp, after two southbound vehicles collided south of the Waimakiriri River bridge about 5.18pm.
Police said a van crashed into a 4x4 towing a trailer. The 4x4 then left the road and crashed into a tree a short distance from the southbound lane.
The two male occupants of the 4x4 died at the scene.
The van's driver, its sole occupant, was taken to Christchurch Hospital as a precaution. He was helping police with their inquiries.
The police serious crash unit, a police photographer, firefighters and ambulance services were called to the scene.
The deaths have been referred to the coroner.
Police said no details would be released until they had been formally identified and next of kin had been informed.
Police closed the motorway while the serious crash unit completed its scene examination.
It was expected to reopen about 10pm.
Six others in the minivan and two occupants of the car were treated for a range of moderate to serious injuries at Tauranga Hospital.
Earlier, three people were killed when two vehicles collided head-on near Marton, at the intersection of State Highway 3 and Williamson Line, about 4pm.
Two of five occupants of a Holden Commodore - Jennifer Susan Town, 41, and her 14-year-old son Zane William Town, both from Whanganui - died at the scene.
Palmerston North woman Judy Daryl Redfearn, 68, who was one of two occupants in a silver Mazda, also died.
A pair of single-fatality crashes brought the weekend toll to eight.
Police said a motorcyclist died after a serious smash in Warkworth late last night.
The crash, involving four cars and the motorbike, happened near the Satellite Station Rd intersection about 9.15pm.
Earlier yesterday, a passenger died and a driver was seriously injured after a car crashed into a tree on Clevedon-Kawakawa Rd, near Clevedon, about 3.45am.
Road policing Assistant Commissioner Dave Cliff said this weekend's road toll was a "preventable tragedy".
"Particularly because it comes right at the end of the United Nations Road Safety Week, where we have been focusing on, particularly, prevention of casualties among children around schools.
"Although these crashes don't involve that, just to lose so many people over such a short period is a real gut-wrenching thing for those people who are affected.
"I think we've come to see road deaths now as entirely preventable."
Mr Cliff said it was too early to say what had caused this weekend's crashes.
"There is really no pattern. The investigations take some time before you can start to attribute particular causes to what went wrong, but what we have been talking about for some time is about a safe system.
"You can get enormous value from doing things like removing roadside hazards, power poles on the side of the road, culverts, trees, that people can hit in a crash and end up being killed or seriously injured."
He also said putting wire rope barriers down the centre of roads helped reduce the chances of a head-on collision.
"We know that on most of New Zealand's rural road network, which doesn't have any median division, the speed limits are often too high on those roads, so we know that reducing speeds on those roads is one of the key things we can do to reduce road trauma.
"We understand what the safe system is, it is just the implementation of it, and we are working through that.
"At the moment, to have so many killed, is all completely unnecessary. I think that is the tragedy of it."
