Early reports suggested someone had been stabbed but police confirmed there wasn't any evidence to back that claim.
A person at the local campgrounds at the time told Hawke's Bay Today that there were "loads of drunken older teens/young adults" hanging around a near by paddock, with many starting to drink very early on in the day.
They also said that from about 11pm till early the next day there was a strong police presence around the area.
Officers are continuing to investigate and expect to make more arrests.
They are urging anyone with information to call 105 or Crimestoppers anonymously 0800 555 111.