"The incidents were serious acts of bullying perpetrated by a small number of senior boys and in no way represents the values and core culture of our school or our boarding institution," the statement said.
"We are devastated that a small group of boys have failed to assimilate any of this message which in turn has had a negative impact on some of our junior boarding students."
Fairfax reported the incidents involved groups of junior students being encouraged to fight after lights out by the senior students.
The school had been in correspondence with the parents of the students involved and support and guidance for the junior students had been put in place, the statement said.
"The college will now investigate the issue more broadly with the intention of understanding how these incidents came about and how to ensure that these similar matters cannot occur again."
The college was considering the most appropriate way to involve the police, it said.