"Some students took photos, some students distributed them, some did both."
Some students were in the photos, he said.
"I don't want to go into the details because I don't think it is appropriate. What I have said is there are a variety of images that have been posted and they are all inappropriate enough for them to be suspended [and excluded]."
Suspensions were handed down by senior management last week and the students appeared before the board of trustees this week, when the decision was made to exclude them.
"There is no doubt that their behaviour was inappropriate.
"They breached our code of conduct and our school rules and are no longer part of our community."
The incidents follow a series of lower-level punishments being meted out to a number of boys at the school for their involvement in a Facebook page last month.
"It's quite a dangerous device that they have before them and many of them don't actually have the maturity to handle it," said Mr O'Connor.
"They are native users of social media and digital technology but what they don't have is the maturity to know what is appropriate to post in a digital environment and what isn't.
"That requires some significant education and we do undertake some of that but we are going to undertake more of it ... so that they understand the ramifications of online posts ..."
Auckland City Police community and youth district manager Inspector Ross Barnaby said officers were consulted, but were not taking any action at this stage.
NetSafe executive director Martin Cocker was not aware of the specifics of Grammar's exclusions, but said schools often consulted the agency for advice.
He said any communications that might affect a safe environment were fair game for schools to address.
"Schools have a responsibility to create a safe working and learning environment."
