Two nine-year-old boys have been shot with a pellet gun that was fired into their primary school playground.
A teenager is thought to have fired a BB gun through the fence at pupils playing in the grounds of St Lawrence's Primary School in York on Thursday.
The head teacher said one child was hit on the elbow and the other on the shin, but neither were seriously hurt.
Police are appealing for witnesses and trying to find the person who did it. Meanwhile, the school is open as usual.
Acting Inspector Shaun Sutcliffe said: "This was an act of utter stupidity, causing distress and alarm to young children.
"In this instance, armed officers were not deployed, however, we would warn people who may own air and replica weapons that incidents such as this could turn far more serious, and you could find yourself facing officers with real guns."
The person involved in the shooting is described as having brown hair with blonde highlights. He was wearing a grey Lacoste jacket with a burgundy or red T-shirt and black tracksuit bottoms.