Teachers in Northern Ireland are being assaulted regularly by children as young as five, a teaching union has claimed.
In one case a primary two pupil attacked three members of staff – including the school principal.
The teacher had to remove the rest of the pupils from the classroom for their own safety.
Now Ulster Teachers' Union president Diane Nugent has warned violence in classrooms is at a critical level. She says some children are under so much pressure, both at home and at school, they are "stress time bombs".
"Many of our children enter our schools like little stress bombs ready to explode from home pressures or school pressures," she said at the union's two-day annual conference in Co Down.
"Just this week we have had two reports – and this is not unusual. But even more frightening is the fact that the parents of one child concerned felt that the staff were provoking the child – this child was just primary two age.
"The child in the school had assaulted three members of staff one of which was the school principal. The teacher concerned had to move the remainder of the class to the corridor for their own safety until the child calmed down."
Ms Nugent said violent outbursts in the classroom, whether they be one-off incidents or more systematic patterns of behaviour, were "completely wrong" and should not occur.
Attacks on teachers by pupils is considered as third party violence and as such is an occupational health and safety hazard, covered by EU legislation.
In December Education Minister John O'Dowd launched a Tackling Violence leaflet in conjunction with the UTU, and vowed to treat the issue seriously.
"As other organisations have already adopted a zero tolerance approach to violence or abuse of their staff, quite rightly so the same high standards should be applied within education," she said.
Between 2011 and 2012 1,393 pupils in Northern Ireland were suspended from school for verbally abusing staff.
Some 164 were disciplined in this way for attacking staff. Of those, 21 were girls.
'I've been thumped, kicked and spat at'
An anonymous Co Antrim teacher who has been off sick since being struck on the head by an object that was thrown by a pupil in the classroom:
"I have whiplash and haven't been able to work since.
"This pupil had been trying to bite me, slap people, hit me with furniture, tried to choke me and then it escalated.
"I was hit in the leg with a missile and then the head.
"I've been teaching for decades and I always liked working with children with difficulties.
"All children are entitled to an education, including those with challenging behaviour.
"In the past I've been hit, thumped, kicked, spat at, chased, pushed up against a wall – I've lost count of the number of attacks.
"It just goes with the job. I got into teaching as I wanted to help. I believe the child who attacked me should have been given one-to-one teaching, but there isn't the money for it; therefore I got hurt.
"Parents used to have a big respect for teachers but that has changed.
"We hear about children having rights but the teachers and classroom assistants have a right to a safe environment too."