A 17-year-old boy was arrested for killing his teacher in the northwestern German town of Ibbenbüren, authorities said on Tuesday.
The shooting took place at the vocational school where the 55-year-old teacher worked.
After the crime, the boy called the police and surrendered without resistance, said the spokesperson for the public prosecutor's office in the western city of Münster.
Motive remains unclear
The teacher was alone in the vocational classroom on Tuesday afternoon when the suspect visited, according to the investigation.
The boy allegedly attacked and killed his teacher with a knife.
The motive of the crime, why the teacher was alone and how the suspect knew this are unknown.
A large police contingent with several patrol cars, a rescue helicopter and an emergency chaplain was at the crime scene.
The suspect is expected to be appear before a judge on Wednesday, a police spokesperson said.
A student is currently facing trial in western Germany for planning a mass shooting at his school in Essen.
According to the indictment, he wanted to target teachers and pupils.
The student planned the crime with pipe bombs with the intention of it being seen as a terrorist attack motivated by right-wing extremism, said the federal prosecutor's office.