State Highway 16 between Helensville and Wellsford remains closed at Makarau, north-west of Auckland, following an early morning unexplained death

Police say it's highly likely the person - who's body was found on the highway - was struck by a vehicle.

Another person's been found dead after a crash on the Hauraki Plains south of Paeroa after midnight - the fifth confirmed road fatality of the summer road toll period.

National Road Policing Manager Stephen Greally is pleading with drivers to keep to the speed limit.

He says whenever Police see motorists driving fast, it worries them, as frontline officers are the ones seeing the trauma that results from high speed crashes.