A prison officer and a prisoner were both injured during a five-hour protest by inmates in Shropshire.
Nine prisoners barricaded themselves in a classroom at Her Majesty's Young Offenders' Institute Stoke Heath at 0900 GMT.
It took staff until 1400 GMT to restore order, the Ministry of Justice said.
The protesters have been split up and moved to other prisons. The Ministry of Justice refused to say what the inmates were protesting about.
"One officer was treated locally for an injury sustained during the incident and one prisoner received a superficial injury which did not require treatment," a spokesman added.