The Upper Hutt College community is in shock over a violent attack on one of its students, which was filmed and shared across social media.
Police and the school are investigating after the video emerged showing two junior students attacking a senior, as others look on.
The Year 9 and 10 assailants are set to find out on Monday if they will be suspended.
The video - which RNZ has chosen not to republish - showed an Upper Hutt College schoolgirl lying on the ground as two younger students pulled her hair and released a flurry of kicks and punches to her head and body.
At least five students could be seen filming on their phones, while a dozen or more looked on. The brutal attack took place at lunchtime last Thursday.
One mum spoken to by RNZ said the violence was confronting.
"It was sad and it made me sick, and I was disgusted by those girls and what they did ... also disgusted with the girls that were around it, filming it, laughing ... that's not funny," she said.
"I do hope that those girls get very serious consequences for that because it's not good. They've done it once then they'll do it again ... actually I'd like to see them expelled from the school really."
The Year 11 victim was left bruised by the attack, and her family contacted police.
Another student's father said he was glad the authorities were involved, and said it was a sad situation all round.
"Now it's up to police and parents of the girls to then work out what they're going to do. I mean, it's going to be tough for those girls now to get into other schools and things like that ... how to solve the problem? Don't know."
The attack had also affected the wider student body, he said. His son was not there when it happened, but did mention it when he got home.
"He didn't really want to talk about it. He said one of his friends was really withdrawn and quite saddened and upset, and just needed some extra comforting," the man said.
"So it affected a lot of the kids who witnessed it."
Principal Judith Taylor declined RNZ's requests for an interview, but said in a statement the attack was unprovoked and happened despite teachers doing lunchtime patrols.
Footage of the assault was shared with other young people within an hour, and later by adults on local social media pages - which the principal says re-traumatised the victim.
The two junior students were not currently at school, Taylor said.
One parent said it was hard to tell whether a similar attack could happen again.
"Is it a one-off? I don't know. And that is it, I don't know. My child will continue to go here because I want to give it a chance. I think the school has done enough to warrant parents' faith in them."
On Monday, the college is starting to implement an online portal so students can report harm anonymously.
Taylor said students were scared to speak up about bullying because there was an "insidious" culture of 'snitches get stitches' in all schools.