The deadly crashes, which claimed six lives, happened in Mercer, New Plymouth and Rotorua, with another two in Whakatane.
Police assistant commissioner Dave Cliff said initial investigations suggested drink-driving, speeding, and in one case a person not wearing a seatbelt were factors in the crashes.
"Three pedestrians have been killed which is really unusual," he said.
Mr Cliff said some drivers incorrectly thought they only had to exercise caution in known accident black spots.
"The vast majority of these fatal crashes, serious crashes, happen in locations where there hasn't been one before. So there's never a good place to be exceeding speed limits."
He said complacency about drink-driving was of concern this weekend.
"You're always unsafe if you're driving intoxicated after you've drunk alcohol," Mr Cliff said.
In another case, Mr Cliff said a crash victim was not wearing a seatbelt.
"It doesn't matter whether you're travelling 100km/h or 1 km/h, you can have a crash anywhere and people must wear safety belts."
Police suspected speed was a factor in the crash that claimed the lives of New Plymouth man Ronald Victor McMillan and Nepalese national Alekh Acharya.
Mr Acharya, 22, collided with 67 year-old Mr McMillan, a pedestrian, in New Plymouth yesterday afternoon.
On Friday night, another pedestrian died on Keepa Rd, Whakatane, after a car hit him.
In another fatal crash in Whakatane, a person was found dead on State Highway 30 near Kope Drain Rd last night.
In the fourth fatal smash this holiday weekend, 21-year-old Elisha Areli died when crashing a car into a tree in Rotorua yesterday morning.
Shortly before 3am yesterday, a body was found on State Highway 1 south of Auckland.
Mr Cliff said it seemed roads were not as busy as on other holiday weekends such as Easter. He had received no reports of major congestion or other problems.
Meanwhile, the New Zealand Transport Agency (NZTA) urged motorists returning to Wellington tomorrow to leave early if they wanted to dodge queues likely to build north of Otaki in the afternoon.
"We advise motorists to expect heavy delays, and to perhaps stop in Foxton or Levin for a break beforehand. Alternatively, you could hit the highway before lunchtime and dodge the delays," NZTA regional performance manager Mark Owen said in a statement.
He said in future, the Peka Peka to Otaki section of Kapiti Expressway would offer "a permanent solution" to this congestion problem.
Mr Owen said motorists must remember a 70km/h speed limit applied to the motorway south of Ngauranga, and on SH1 past Poplar Ave.
By John Weekes of NZME. News Service
