www.bbc.co.uk/news/education-29111528
Clearly a distress child should not have been locked in a room. However I can see how it could have happened. I feel that better training could have helped these teachers deal with a diffciult situation better.
For example training teachers in how to restrain a child safely, descalation techniques and improving communication skills would help. A school always has the option of calling the police for an out of control child.