Two were in a serious condition and two had moderate injuries, she said.
A Fire and Emergency New Zealand (FENZ) spokeswoman said two fire engines went to the crash and staff helped the ambulance team administer first aid.
The Serious Crash Unit has been advised.
Last year, eight people died on the country's roads during the official holiday period.
This year, two people have died in crashes since the period started on Christmas Eve.
As of Thursday, the number of road deaths this year sat at 372 - just three fewer than for the same period last year. By the end of last year 378 people had lost their lives on New Zealand roads.
The first fatal crash of the holiday period claimed the life of Whanganui teen Felix Newton.
The 17-year-old died after crashing his ute into the Whanganui River off Victoria Ave Bridge in the early hours of Christmas Day.
Police today warned people to take care on the roads, releasing a statement reminding drivers to stay sober and alert.
In 2017, driving under the influence of drugs was a factor in more road deaths than alcohol.
Superintendent Steve Greally, National Manager for Road Policing, said nobody should get behind the wheel if they were impaired by drugs or alcohol or if they were too tired to drive.
"And nobody should get in a vehicle with a driver who is in that state either."
It was not worth risking your life, Greally said.
"Driving tired can be as dangerous as driving drunk or drugged; your reactions are slower and it's hard to concentrate."
That was not a good combination when you're in charge of a two-tonne vehicle, he said.
"Take breaks and share the driving when you can."
It was important to make sure the driver is fresh and alert, he said.
"When you're making your plans for New Year's, make sure they include how you're getting home.
"Be realistic; if you think you may end up drinking, don't drive."
