Two Wellington College pupils have been referred to Youth Aid after another student was shot in the temple with an air pistol.
Headmaster Roger Moses says the boys were firing the pistol at random and the pellet ricocheted, hitting another who was walking into Newtown Park to take part in a school sports day.
The boy initially thought he had been hit by a rock, then discovered the pellet in his head.
He was taken to hospital where the pellet was removed.
Mr Moses says it's not the crime of the century, but the boys made a silly decision and the board of trustees will decide on their punishment.
He says they have apologised both to the school and the boy who was injured.