Sweden's national bomb squad were called to a preschool after a child brought a live grenade into class, sparking panic.
The incident, which occurred in Kristianstad in southern Sweden, ended with the bomb squad neutralising the device but the officer in charge said it "could have gone really badly".
Staff called police after finding the device in the evening, after children had left for the day.
Police then identified it as a grenade and called the bomb squad, who assessed the grenade as too dangerous to move and dismantled it at the scene.
A spokesperson told CNN that a child found it at a nearby military training ground: "The military uses these big open fields for exercises, but at certain times of year they are open to the public when there's no shooting going on and people are told not to touch anything out of the ordinary."