A 17-year-old male pupil is believed to be the perpetrator of a knife attack at a grammar school in the western German city of Wuppertal, the region’s interior minister said on Wednesday. Herbert Reul, the interior minister of the state of North Rhine-Westphalia, which includes Wuppertal, confirmed the weapon used but said nothing is yet known about the motive. The attack wounded four students. Reul said it is currently assumed that he was a lone perpetrator.