Rival gangs fought with a hammer in front of children at recent Matariki celebrations in Wairoa, Hawke's Bay.
Mongrel Mob and Black Power members got into the scrap at a community celebration on Friday.
Both gangs fled the Wairoa Community Centre before police arrived at the scene, Senior Sergeant Tony Bates said.
Police had seized a hammer they believed was used and would be speaking to both gangs.
It had "blighted" a community celebration and set a bad example for children, Bates said.
"This was an unfortunate incident that detracted from the whole event, which was meant to promote community spirit and a celebration of a special event.
"Our community deserves to be able to hold these events without fear of violence or gang conflict."
- The Dominion Post
Testing drugs on animals is:Related story: Animal tests 'key' to brain disease cures