Police have referred two girls to Youth Aid in relation to the assault of a girl at Creekfest in Porirua at the weekend.
The 12-year-old and 15-year-old were filmed viciously attacking a girl at the family event on Saturday.
It was described by police as "a disgusting act of violence".
Kapiti Mana senior sergeant Grant Ferguson said: "This incident highlights the fact that we still have a lot of work to do around how violence in the home and in our community can influence a young person's behaviour."
He said while the damage can't be undone, police and the community can work together to prevent further violence in the future.
"Police acknowledge the emotions of anger and resentment in the community towards the actions of these girls, and we would like to thank the public for their support and assistance with the investigation."
He said the matter is being dealt with appropriately, "and the people involved need our support to enable them to change their behaviour".
Festival organiser Liz Kelly, from Porirua Whanau Centre, previously told Newshub the incident didn't reflect the positive vibe of the 32,000 people who attended the festival.
"It had nothing to do with the Creekfest and it's really unfortunate. My heart goes out to the victim and her whanau."
Ms Kelly says despite its reputation Porirua is generally a positive community.
The festival has been running for 12 years and there's never been any violence. It promotes healthy living, connecting whanau and anti-violence.