A violent schoolyard attack in which a crying girl is repeatedly punched and kicked in the head has been posted on social media to raise awareness about bullying.

The "disgusting" video, believed to have been filmed last week, shows a Year 9 girl being hit with a swinging punch from a fellow student before being pulled to the ground by her hair.

She is then kicked in the face with a jarring blow that jolts her head back.

A teenager who sent the video, which has since been removed from online, to the Herald says she wants to highlight the violent bullying happening at schools, which parents may not be aware of.

As the victim lies clutching her face, a second kick is fired in. Hunched and still cradling her face, her hair streaming down, she desperately declares: "I didn't do anything."

"I didn't say anything, I swear."

Other students can be heard telling her to "hurry up, just get up".

When she stands, still holding her face and crying, she again pleads with her attackers: "I really didn't say anything, please just leave me alone."

"I promise I didn't. I swear, I don't even know who you are."

But as she tries to walk away, the attacker and another student hold her back and throw more kicks and punches that connect with powerful slaps.

A boy tries to intervene, telling the attackers to stop, but the main attacker turns on him with repeated punches and kicks, before again knocking the girl to the ground under a hail of blows.

It is not until another student intervenes, saying "leave her alone, go away" that the attackers relent.

The mother of the boy who defended the young girl told the Herald the incident wasn't simply a school fight, it was an attack.

She said her son, aged 14, and the girl who were attacked were both in Year 9 but did not know the students who attacked them.

"That wasn't a fight, I've seen a school fight … that wasn't one, that was an attack."

"The video was really scary, it's hard to watch and it makes me really angry. That was a blatant attack, that wasn't anything else."

Despite also being punched and kicked during the attack, the mother's son came away relatively unscathed but she was keeping an eye on him.

She believed the girls throwing punches and kicking the other girl should face real repercussions for the harrowing ordeal.

The high school has not responded to multiple requests for comment by the Herald.

The video was posted on Facebook yesterday after being shared among students.

It was sent to the Herald by a young student from another school - who described it as "disgusting" - in a bid to raise awareness about bullying.

"(I shared it) for an eye-opener to the parents so they know what goes on behind the scenes at school," she said.

"For instance, there is a lot of kids that would rather sit in the dark rather than talking to their parents about it."

"I was hoping that the parents could see that maybe their child could be skipping school because stuff like this is happening but doesn't want to talk about it."

The student said she felt compelled to act because the video had been getting passed between students, but "no one was doing anything about it".

She planned to go to the police today because she thought she knew who the attackers were.

Children's Commissioner Andrew Becroft said a zero tolerance to bullying culture was needed.

"When it comes to reported bullying in secondary schools, we lead the world and that is a natural disgrace," he said.

"Bullying is unacceptable and children need to be able to report it without fear or shame."

He said a Bullying Prevention Action Group had been active, providing helpful guidelines over the past 4-5 years.

"But too much has been left to schools to implement on their own. We need a school-wide culture of zero tolerance to bullying."

Every school needed to start collecting statistics to show what was really going on so that interventions could take place for the "bullied and the bully".

"We need to be much clearer now and make it an obligation that every board of trustees has in place a validated and effective bullying-prevention programme," he said.

"This must be mandatory and compulsory in all schools."

Netsafe director of education and engagement Sean Lyons said caution needed to be exercised when spreading videos on Facebook.

"I understand the need or desire of some people to get a message out," he said.

"But the thing we all have to be careful about when we choose to spread something that is potentially harmful to an individual is that we can have the unintended consequence of being a part of that harm."

The original Facebook message by the girl who sent the video to the Herald stated: "I am not the one recording. This is exactly why society is getting worse. Makes me sick. No one deserves to be hurt like this. Nor going to school feeling unsafe. This is not cool, and most definitely not okay."

Police had been made aware of the incident and their inquiries are ongoing, a spokeswoman said.

Police have asked anyone who has been assaulted to contact them, saying all students had the right to "feel safe and secure within the community".