In the video one boy is seen hurling a brick at another. The brick hits a second child on the head as shocked pupils watched - but it is unclear what led to the incident.
Yesterday the father of the victim refused to comment and said that the incident is being blown out of proportion.
"You choose what you want to write, I have nothing more to say on this," he said.
Both boys are in Grade 8.
In a statement, the school said: "The governing body and management is treating this in a very serious light and will follow procedures prescribed by the department to address the issue."
Chairperson for the school governing body, Ati Butler, said this type of behaviour was unacceptable.
"I will try to run a programme at the school again that showcases school violence and bullying . this type of behaviour is not in line with the school's code of conduct," said Butler.
Butler warned that pupils could be expelled once the investigation is complete.
Spokesperson for the Western Cape education department Paddy Attwell said they were aware of the incident and that an investigation was under way.