Johnston said police were also investigating an assault on a group of tourists who were parked nearby in a designated freedom camping area at Lindvart Park.
That incident was reported about 10pm on Saturday night, several hours before the alleged stabbing at the party.
''A group of tourists had parked their campervans near the park and were catching up when they were approached by a group of aggressive youths. That group have smashed the windows of their van, assaulted several of the tourist group and then stolen some of their property,'' Johnston said.
Police were examining town CCTV footage and following up leads that had been provided already.
''Any offending against tourists in Northland is treated very seriously. It's an offence against all Northland residents as tourism keeps our region going," he said.
The stabbing and the assault on the tourists were likely to be connected due to their proximity and closely matching descriptions of the offenders.
Anyone with information about the incidents was urged to call Kaikohe police on (09) 405 2960 or Crimestoppers, anonymously, on 0800 555 111.