Four students were wounded in a stabbing on Thursday at a school in the western German city of Wuppertal, with a suspect – believed to be a student himself – was arrested at the scene.

The incident took place on Thursday morning at the Wilhelm Dörpfeld high school in the city of some 350,000 people near Düsseldorf and Cologne.

Police say four students were wounded, as was the suspect, German news agency dpa reported.

The top regional security official, Herbert Reul, announced that the attack was apparently carried out with a knife by a 17-year-old student.

Reul, the interior minister of North Rhine-Westphalia state, said that at least two of the victims were seriously injured, as was the suspected assailant.

He told the state legislature’s home affairs committee that he had been told the suspect inflicted injuries on himself. There was no word on a possible motive, and the suspect was believed to be a lone assailant.

Other students were evacuated from the building after the attack.