Sergeant Maria Nordstrom, of Dargaville police, said seven young people were believed to have been in the north-bound Subaru car when it crashed off a moderate "S" bend on the road and landed on its roof in a deep ditch beside the road.
Two passengers were airlifted to Whangarei Hospital with serious injuries. Two rescue helicopters from the Northland Emergency Services Trust attended the crash scene and late yesterday morning one of the choppers transferred the two seriously injured men from Whangarei to Auckland Hospital because of the nature of their injuries.
Three other men were taken by ambulance to Dargaville with moderate injuries.
Firefighters from Dargaville had to cut one man from the wreckage using the jaws of life and Pouto Rd was closed for several hours while emergency services staff cleared the scene.
Ms Nordstrom said the weather was fine, the road dry and traffic light at the time of the crash.
The crash brought the number of fatalities on Northland's roads in 2012 to 13, almost double last year's record low road toll of seven.
Anybody with information on the accident, or who may have seen the Subaru travelling on Pouto Rd before the crash, can contact Dargaville police on 09 4393400.