Sadly this poor level of behaviour and disruption is not uncommon in secondary schools. Teacher assaults by pupils are growing in numbers, both verbally nd physically. It often is not related to overal control a teacher has - it is more to do with senior management and they way they support teachers when clsses behave like this.
I myself was physicaly assaulted as a teacher at schoo. I as 7 months pregnant and a 13y slammed a chair into my stomach and then walked out smashing two windows. I was in control of everyone else in that classroom, until the time he lashed out all had been fine, I had calming asked himt o get on with his work - not a shouter here. Teachers of all standings can be assaulted.
However, this does not in anyway condone the actions of this teacher, who obviously had cokpletely lost it. He had already had lengthy time off after cncerns he might hurt someone (he felt it about himself if BBC reports were correct).
I would also question his return to work and why, after such lengthy time off and for the reasons he was off, why he was placed in such class in this situation. i think management need to consider their policies on return to work.
Again thouh - regardless of all this - the teacher was very much in the wrong here. He reacted entirely inappropriately and there appears to be intent to hurt - albeit their maybe some medical concerns behind this reaction at this time.
I hope the teacher is punished appropriately and also gets the medical help they clearly require in order to live safely in society.
I also hope that the other school children were not too traumatied by what they saw, but that they have also realised how their own actions are called into question on this day and in the lessons prior, and how they need to address their own behaviours and have some respect for other people besides themselves.