Four pupils have been expelled from a successful Swansea school for bringing two air pistols on to the site - and firing pellets at a fellow student.
The teenager was not injured in the incident earlier this month at 2,000-pupil Olchfa comprehensive, although a pellet skimmed the back of his head.
In this summer's GCSE exams, 72 per cent of pupils passed at least five subjects at grades A* to C.
Governors meet next week to review head Hugh Davies's decision to permanently exclude the four Year 9 boys. The boys' parents could then appeal to an independent panel.
Mr Davies said he had not yet written to other parents about the incident for fear of prejudicing any appeals. But he may now do so to keep them informed, following press reports.
"One of our concerns is the sanctity of the whole appeals procedure. It's right that any head should be accountable to the governing body and any independent appeal panel," he said.
The incident happened during lunchbreak on October 1, on the edge of the school's site. The victim did not report it to staff until the end of the school day. An assistant head then contacted police the following Monday, and the school launched its own investigation.
Mr Davies said: "When we investigated, it became clear that two air pistols had been brought to school and had been fired at another pupil. I then issued temporary exclusions for four pupils. On Friday, October 8, I permanently excluded four pupils.
"The school governing body's discipline committee has been convened to hear four appeals next week, and thereafter the parents have the right to appeal to an independent panel."
He added: "I can't guarantee that no air gun has ever come on to the premises, but we have never had an incident of this type before. The gravity of the event is signalled by the action taken."
A South Wales police spokeswoman confirmed that it was still investigating, but said such incidents were extremely rare.
She said: "We are always asking parents to be mindful about buying these weapons for children, and strict laws about their use were introduced in January."
The minimum age for owning an air gun was raised from 14 to 17 in January, and from April 30 owners have been required to have a full firearms certificate. A campaign to get unwanted weapons handed into police was endorsed by the National Union of Teachers Cymru.
Heledd Hayes, the union's education officer, said: "We would support firm action making it clear that bringing a weapon to school cannot be tolerated."