It's two fewer than Labour Weekend last year, when five died, and two more than 2013, when only one person lost their life - the lowest road toll since records began in 1956.
Despite the relatively low number killed this weekend, road policing assistant commissioner Dave Cliff said it was still three too many.
He said a number of critically injured people were still fighting for their lives in hospital after crashes this weekend.
"We have people across the country with horrendous internal or head injuries after road crashes that were entirely preventable."
He said a large number were not wearing safety belts, including a young man hospitalised with "catastrophic" injuries after a crash.
Cliff said the man was sitting in the back seat of a car without a seatbelt.
"Rear seat passengers can be thrown forward and killed or injured.
"But wearing a seatbelt is also about protecting other people inside the vehicle, as back seat passengers can also injure or kill others inside the vehicle.
Typically, Cliff said, 60 people who were not wearing seatbelts died each year in crashes - but this year's stats had already superceded that figure.
So far this year 70 who weren't wearing a seatbelt had been fatally injured in a crash.
Given the rate of fatalities Cliff anticipated another 70 could die in crashes on the country's roads and anticipated another 600 could be seriously injured.
In the lead-up to Christmas, police would put a "massive" focus on making sure everyone is safely belted into cars, he said, including children and babies in car seats.
"It's crazy that in this day and age people are letting their children travel unrestrained."
The first Labour Weekend death was early Sunday morning, when a car struck a median strip and a truck on the Southern Motorway, near Pokeno, just after 4.30am.
Details of the person killed have not yet been released by police and the Serious Crash Unit is investigating.
In the latest crash emergency crews were called to a collision between a car and a motorcycle near Wallacetown, Southland, about 3pm yesterday.
A 56-year-old man died at the scene, near the Underwood-Linds Bridge. It was unclear whether he was the motorcyclist or in the car.