Police officers in Auckland were pelted with bottles during a skirmish involving partygoers in the early hours of Sunday morning.
After a party at a house in Castor Bay on the North Shore, shortly after midnight on Saturday, police received reports of young people damaging letter boxes and standing on cars.
Police say bottles were thrown at officers trying to disperse the group of 150 partygoers. A police helicopter was called in to help break up the crowd.
Four people were taken into custody, but later released, and others were cautioned.
Police say there were other incidents of drunken disorder across the North Shore and in South Auckland on Saturday, describing it as the beginning of the silly season.