Almost one in ten secondary schools has caught children bringing guns to school, a survey has found.
Knives are even more commonplace, with more than 40% of teachers saying pupils are carrying them, according to the education newspaper SecEd.
Other violent children adopted everyday objects as weapons, such as chairs, cigarette lighters and tables.
Eammon O'Kane, general secretary of the NASUWT union, said "These results are a snapshot of what has become a very worrying trend right across the country.
"The government's attempts to tackle the problem with truancy sweeps and on-the-spot-fines for anti-social behavior may alleviate the problem outside school, but steps must be taken to protect teachers in the classroom."
Staff are becoming increasingly concerned over the prevalence of weapons in the classroom, with 63% of those who took part in the survey saying they are a problem.
Serious attacks have been reported involving bats, bricks, axes, metal bars and even home-made bombs.
Gerald Imison, joint acting general secretary of the Association of Teachers and Lecturers (ATL), adds: "The survey would support ATL's feeling that children in schools increasingly see violence as a routine part of every-day life.
"Unfortunately, schools that try to tackle these issues often find inadequate support from their local authority or from the government."
The survey also found 28% of teachers had been threatened with violence by a student and 6% by a parent.
Meanwhile, 15% had been physically attacked by a student and 1% by a parent.
SecEd questioned 160 teachers for the survey.