A New Plymouth college staff member suffered broken ribs last week when he was attacked by a special needs student brandishing a length of wood.
Spotswood College principal Graeme McFadyen said the year-nine boy "lost control" and hit a man who worked part time as a security guard at the school.
The boy did not have a history of such behaviour and did not pose a risk to anyone else at the school, he told the Taranaki Daily News.
He was normally accompanied by a teacher's aide while on school grounds, but the aide was away sick on the day of the attack.
"These things will happen, we have got 40 special needs young people in our college.
"We do our best to care for them and we have got a really good reputation as being a very caring college that does really well for these young people."
Mr McFadyen said the boy was stood down for a week with his parents' consent.
