Five students are said to have been wounded in an apparent knife attack in the western German city of Wuppertal.
Police say they have arrested a suspect, who is also thought to have been hurt.
An unconfirmed report from Bild newspaper said the students were attacked by a classmate, although details are unclear. A female teacher said the pupils had been attacked with a knife and a pair of scissors, German media reported.
Teenagers at the Wilhelm-Dörpfeld secondary school are then said to have barricaded themselves in their classrooms. A major police operation began shortly before 10:00 (09:00 GMT) on Thursday.
“Students have been injured,” police said in a statement on social media, adding later that the school had been cleared and all the students were safe and being looked after. Police spokesman Stefan Weiand told the Westdeutsche newspaper that the students were “understandably shaken”.
— CutC by bbc.com