The male front seat passenger was critically injured and airlifted to Waikato Hospital.
Police said the initial scene examination has also shown that the rear passengers in the car were not wearing seatbelts.
The truck driver was shaken but not injured.
Police were able to confirm that the people in the car were foreign nationals but no further details, including nationality, would be released until next of kin had been notified.
Police were working to re-open the road as soon as possible.
Earlier story: Three people have been killed and one critically injured in a crash between a car and a logging truck on State Highway 1, north of Tokoroa.
Emergency services are at the scene between Litchfield and Tokoroa where the crash occurred just before 4pm today.
"Three have died and one other was being retrieved from the car in a serious condition and will be transported to hospital via helicopter," northern Fire Communications shift manager Scott Ormond said.
Inspector Willie Taylor from the police northern communications centre said it was too early to say what caused the crash, but the serious crash unit and the commercial vehicle investigation unit would examine the scene to determine what happened.
One person was in a critical condition, he said.
Police said the road has been closed and is likely to remain that way for some time.
Diversions are at Wiltsdown and Rollett Rds.
Police are asking motorists to avoid the area if possible and expect delays.
