Police are investigating the death of a man, 24, at Omamari Beach near Dargaville.
He was found unconscious on the side of the road early on Sunday morning.
An ambulance was called but he died before it arrived.
Police say the Dargaville man had earlier sustained a deep cut to his arm after putting it through a window during an argument at an Omamari party.
They say he lost a lot of blood from the injury.