Four school pupils were injured by an attacker at a school in the western German city of Wuppertal on Thursday, according to a police spokesman. The suspected attacker, who is in custody, is also a pupil at the school, sources told dpa. According to police, the suspect was also injured in the incident. Police thoroughly searched the school after an evacuation was carried out, the police spokesman said. The police did not initially provide any further details about the crime or the background. The Bild newspaper reported that a teenager is said to have attacked his classmates with a knife.