Five students were hurt in a stabbing at a school in Wuppertal, Germany.
The police have caught someone they think did something wrong, and they might also be injured.
According to a report from Bild newspaper, students were attacked by a classmate, but we don’t have all the details yet.
A woman teacher told the news that students were attacked with a knife and scissors.
The students at Wilhelm-Dörpfeld secondary school locked themselves in their classrooms.
A big police operation started just before 10:00 (09:00 GMT) on Thursday.
“Students got hurt,” said the police on social media. Later, they said the school was safe and all the students were okay and taken care of.
Police spokesman Stefan Weiand said to the Westdeutsche newspaper that the students were understandably scared.
More update on this story soon.