A man has been arrested over an assault at Napier's Anderson Park on Sunday.
It was one of several gang-related incidents in the city that day. Police were called to the park in the afternoon after reports of men fighting with weapons, TVNZ reported.
And a shotgun was reportedly fired in the evening.
A 19-year-old has been charged with causing grievous bodily harm and will appear in court next week.
Police are still appealing for information about the incidents.
"We've seen turf wars down at Anderson Park between Mongrel Mob and Black Power," Det Insp Mike Foster told RNZ.
"It's ramping up, so we've got staff visible down there at the moment."