Ashburton Intermediate is dealing with an incident where a female student was recorded being assaulted by another girl at school.
Principal Brent Gray confirmed the attack had been circulated online and was being dealt with, but he could not divulge any further details, citing privacy reasons.
"There was an assault captured on video last week, which was extremely disappointing and distressing for all involved, especially the victim," Gray said.
"We have worked closely with all families concerned and also contacted the police so that they were aware of the incident."
The school's board was working through its policies and procedures in dealing with such a harmful situation, he said.
"We are in regular contact with the victim and their family to support them on the student's return to school."
The incident came at the same time fresh bullying allegations have come to light at Ashburton College.
Gray, as the Mid Canterbury Principals' Association chairman, said: "Many schools will be dealing with these issues, unfortunately, on a daily basis.
"There are clearly differences between the assault and incidences of ongoing bullying, although we also know these can go hand-in-hand.
"Knowing about these incidents and taking the time to deal with them can be ongoing."
Individual schools would have their own policies and procedures around dealing with bullying, he said.
He said social media played a role in many of these situations and parents and caregivers were often referred to Netsafe, New Zealand's online safety organisation, and the police if it was happening outside of school.
"It is clearly an issue for families and schools. And, in most schools, education around this is increasingly becoming part of the yearly programme, even though many social media applications are age restricted," Gray said.
Local Democracy Reporting is Public Interest Journalism funded through NZ On Air