Police are investigating after a 15-year-old allegedly stabbed fellow pupils with a sewing needle at a school as they travelled home on a school bus.
Pupils are alleged to have been attacked with a sewing needle
Children from West Monmouth School in Pontypool, south Wales, had to undergo medical checks for hepatitis B after being attacked with the two-inch needle.
The boy allegedly began jabbing pupils while waiting for the school bus home and continued the attacks on the journey.
According to the school's headmaster, Peter Phillips, up to 20 pupils - all of whom have been advised to contact their GP to be tested for communicable diseases - were attacked.
Parent David Parry said his 14-year-old son Lee - who arrived home with blood on his shirt after being stabbed in the chest - had undergone blood tests and had a hepatitis B injection, which is set to be followed up with a series of booster jabs.
"He is not worried about it," he said. "I wouldn't say I was 100% - I will be more content when the results come through."
The pupil was excluded from the school following the attacks, which took place on 30 January.
Mr Phillips said the incident was being taken "very seriously".
He told BBC Wales News Online: "The incident took place on the Friday afternoon and the school first knew about it on the Monday when some parents contacted us to say their children had been stabbed.
"The 15-year-old had obtained a sewing needle and he began sticking it into a number of people as a prank.
"When we got together on Monday, I gathered around 40 pupils, aged between 11 and 16, who may have been involved or seen something.
"Of these, 10 to 20 actually came into contact with the boy. Some of those would have had their skin punctured, while others would have pushed the boy away.
"But I contacted NHS Wales, gave them the details of every child who could have been touched by the boy and advised parents to take those children to their GP."
Mr Phillips added: "The allegations are very serious, but I don't think the boy realised it.
"It's one step up from the old prank of placing a drawing pin on a teacher's seat, but if you puncture the skin, you could be transferring anything.
"The boy has been excluded and is unlikely to return to school."
A spokesman for Gwent Police said: "We have had an incident reported to us and inquiries are continuing."
A spokesperson for Torfaen Council said: "There was an incident on a school bus which was a prank that got out of hand."