Six Ashburton College pupils "mimicked" media portrayals of a terrorist group by putting a cloth bag over the head of a 13-year-old while others told the victim "this is just like Isis".

Principal Grant McMillan said the incident on Friday resulted in three "leaders" of the group being stood-down for five days, after which time they would return to school.

Referrals had been made to the police, Child Youth and Family and mental health agencies, he said.

In class at about 1.30pm, the group began "shoving" the boy.

"Then to top it off one of them thought they would be clever and put his manual technology bag over his head," said McMillan.

He said two or three of the group "mimicked Isis" and said: "this is just like Isis".

"The additional elements that will have everyone excited and frothing at the mouth – adults will understand what that means – 14-year-old boys don't," he said.

"[We are] more than confident that a couple of kids were acting like twits trying to be clever in the same way in the 70s when kids claimed they were in the Black Power and they weren't," he said.

"We forget the power of global media on our students. We saw that with tourists and car keys last week," he said.

The victim was OK, he said.

"Our No1 priority has to be the student who was bullied," he said.

"We have taken the bullying and additional elements really seriously."

The families involved were "mortified", he said.

McMillan said within five minutes of the incident, pupils in the same class reported the incident to teachers.

The school spent the weekend plus Monday investigating the incident.

"The stand-down time will give us time to look at what we will have in place when the students return and also work with their families," he said.