Acid, knives and several other weapons have been brandished among more than 200 violent incidents in Western Bay of Plenty secondary schools since 2005.
Alarming police statistics have also revealed how a 13-year-old who stabbed his Te Puke High School teacher in May was just one of five recorded incidents involving weapons this year.
The other four incidents involved a 12-year-old boy threatening to kill with a knife, a 12-year-old girl and a 13-year-old boy in possession of knives, and an assault by an 11-year-old boy with a knife.
The figures, obtained by the Bay of Plenty Times this week through the Official Information Act, show there were 206 incidents involving assaults between 2005 and July this year.
Police were required in 176 of the cases - the remainder being reported simply for information - and of those, 32 involved weapons of some description.
In other serious cases, a 13-year-old boy was found with an air rifle, a 10-year-old boy and a 13-year-old boy used knives and threatened to kill, and two 11-year-old boys were involved in assault with an intent to rob.
While police recorded most incidents as common assaults or threats, more serious cases involved threats to kill, apprehensions for robbery and acid being thrown with the intent to injure.
Of the total 202 people apprehended by police, five were as young as 10 and 59 were female.
The figures did not surprise Relationship Services area manager Ash Smart.
"We are noticing some concerning trends ... there seems to have been a jump in the intensity in the violence and there has been growing violence among young females."
Mr Smart had "no doubt" violence in schools was worsening, as was the rate of weapon-related incidents.
However, only a "very small element" of youth were involved - many of who were already exposed to violence in the home or among friends.
"And often these kids are either on the cusp of offending or have already offended," Mr Smart said.
His agency succeeded in getting troubled youths back on track in 80 per cent of cases and often through the intensive Positive Pathways programme run jointly with ImpacTauranga and Child, Youth and Family.
ImpacTauranga manager Nynette Martin said further work was being done directly with Bay schools, while alternative education for pupils stood down from Katikati College, Otumoetai College and Tauranga Boys' High School and Tauranga Girls' High School was achieving good results.
At Mount Maunganui College, a zero-tolerance policy on weapons meant any pupil caught carrying one was swiftly stood down.
Mount Maunganui College principal Terry Collett said pupils fighting at school were first referred through a restorative process involving family, which usually resolved matters.
"But if we find there has been no difference in their behaviour, then we have no choice but to suspend them from school."
Secondary Principals' Association of New Zealand president Patrick Walsh said the Government was yet to clarify "search and seizure" rules, which had been demanded after the Te Puke High School stabbing.
Principals across the country were reporting an increase in weapons being brought to school, most being instruments such as knives or screwdrivers, Mr Walsh said.
He suspected the actual number of violent incidents at Western Bay schools to be far higher, given the amount not being reported to police.
"Sometimes a school will sort an issue out by itself if it's concerned about reputation."
NEW FIGURES: STUDENTS WITH WEAPONS
206 incidents involving assaults
176 required police assistance
32 involved weapons
Five pupils as young as 10
59 were female