Oakwood school in Stowmarket, Suffolk, with 43 boys on the roll, was shut down by Suffolk council last week. Frances James, special education manager, said the school's governors had asked the authority to intervene.
"There were times when the behaviour was threatening the health and safety of others. It wasn't continuous, but there were an increasing number of serious incidents. We had around 11 fixed-term exclusions in the week before they closed," she said.
"We were hoping the school would carry on (until the summer). But the situation became increasingly volatile."
The school was inspected by the Office for Standards in Education earlier this year, and found to have serious weaknesses - despite making some progress under an acting headteacher who was drafted in from another school. It had already stopped weekend boarding, and had reduced week-time residence.
A Suffolk spokeswoman confirmed it was unlikely the school would now reopen, and said officials were already making alternative arrangements for its pupils.
Ann Taylor-Zinn, whose 15-year-old son Stephan is due to take GCSEs next summer, said: "It would have been possible to keep the school open for Year 10 and 11 pupils, and also for those who are less disruptive - but the authority didn't wish to do that."