A 13-year-old boy was arrested after taking a stun gun to school and firing it at fellow pupils, police said.
The pupil at Trinity Catholic School in Leamington Spa, Warwickshire, was arrested for being in possession of a prohibited weapon.
Pupils reportedly claimed that the teenager chased students with the stun gun during a lunch break last week.
The boy was suspended but has since returned. No pupils are believed to have been injured, police said.
Police said the weapon was not as powerful as a Taser gun, but could deliver strong electric shocks.
A Warwickshire Police spokeswoman said: "Officers arrested a 13-year-old boy on suspicion of being in possession of a prohibited weapon after reports that a stun gun had been used on three fellow pupils at Trinity Catholic School in Guy's Cliffe Avenue, Leamington Spa.
"The stun gun was seized and locked away by staff until officers arrived at the school.
"The boy was questioned by police and bailed without charge, and we are liaising with the youth offending team."