Police are calling for patience on the roads as drivers head home.
The provisional death toll is the highest King's Birthday road toll since 2016, when 11 people were killed.
Three killed in Desert Road crash
Three people were found dead at the scene of a two-vehicle crash on State Highway 1 near Waiouru early on Monday morning, where two others suffered serious injuries.
Emergency services were called to the scene about 2:55am.
Another person, who police believed was also in one of the vehicles, was initially described as still missing.
A search and rescue operation was launched to locate him, but by Monday evening police said he had been found, there were no further concerns for his welfare, and police were speaking with him.
Police said the two injured were an 11-year-old girl and a 39-year-old woman in a different car.
Ruapehu District Mayor Weston Kirton said the community feels for those involved in any accident.
"It's tragic on a long weekend where it's busy. So we just want to send our sincere condolences to the families connected, and hope that we can get to the bottom of the problems."
Four dead in other crashes
On Waiheke Island, one person died in a single-vehicle crash, police said. Emergency services were called to Onetangi Road, about 1:30am on Monday.
At Wairakei, north of Taupō, one person died following a crash overnight, police said on Monday morning.
Also at Taupō, one person was killed just before 6:30pm on Friday, after a two-vehicle crash at Te Heuheu Road.
Police call for drivers to take their time and drive safely
The number of people affected by the count is "absolutely gutting," Police director of road policing Steve Greally said on Monday morning.
He called on all those heading home from the holiday to take every safety precaution possible.
"We're gonna have a lot of people getting on the roads coming home from the long weekend, and we also know that the weather is going to be really poor - in parts of the country torrential rain, and of course that can be really hazardous as well.
"So we need people to be really patient here."
"We are thinking of their families today, while they deal with the awful reality that their lives will never be the same."
"We say it all the time but we're going to say it again - there are four main things that contribute to death or serious injury on the roads," Greally said.
"Those are speeding, not using your seatbelt, driving distracted, or driving impaired, including by tiredness.
"If you're getting on the road today, please - buckle up, put your phone away, watch your speed, and if you are at all impaired by alcohol, drugs or tiredness, stop - don't get behind the wheel.
"These things might be the difference between you getting home safely or not."
The Desert Road had reopened by midday Monday, but police were still working in the area and asked drivers to be cautious.
The Ministry of Transport said the holiday road toll for King's Birthday weekend is counted from 4pm on the Friday to 6am on the Tuesday.
