German police have arrested a 15-year-old schoolboy suspected of killing a classmate on Tuesday by stabbing him in the neck, authorities and media reports said.
Media reports said the teenager did not resist when police tracked him down through a helicopter search and arrested him.
Prosecutors said preliminary investigations suggest that the boy was not planning a rampage at the school in the western state of North Rhine-Westphalia.
The attack happened at around 8 am (0700 GMT) at the school in Luenen, in the western state of North Rhine-Westphalia.
The Dortmund prosecutor and police, in a joint statement, said the attacker was known to the authorities for aggressive behaviour and had come to school with his mother for an arranged meeting.
While waiting for that meeting he allegedly confronted then attacked his 14-year-old classmate with whom he had already had confrontations.
Regional minister Herbert Reul said he was "shocked" by the schoolboy's death.
According to Bild daily, the suspect stabbed the victim in the neck with a knife in front of his mother.
"The investigation is ongoing," said police of the killing at the Kaethe Kollwitz high school with 1,000 students.
German media said both boys were German citizens, with the suspect also holding Kazakh nationality.
A minute's silence will be held Wednesday at midday in the school and at the city hall of Luenen.