A pupil shot and killed a fellow student at a German school on Thursday, authorities said, in the latest in a series of youth murders in the country.
Police and prosecutors in the southwestern city of Offenburg said they suspected a "personal motive" in the dispute between the two minors.
The assailant was arrested in a classroom at the school where he fired on his fellow pupil of the same age. The victim later died of his wound in hospital.
Around 300 emergency responders arrived on the scene and 180 pupils were evacuated to a neighbouring athletics hall and picked up by their parents.
Germany, where gun crime is relatively rare, has seen a series of deadly incidents involving youths in recent months.
German police arrested two teenagers and seized a pair of "apparent toy weapons" on Wednesday after evacuating a high school in Hamburg over a security threat.