A teacher was killed in a knife attack in a school in the northern French city of Arras on October 13 and the investigation has been handed over to the anti-terrorism prosecutor's office. The regional Pas-de-Calais authority said the suspected assailant, who also wounded a second teacher and a school security guard in the attack, was arrested. The suspect was a Russian-born Chechen and former student of the Lycee Gambetta high school where the attack happened, a police source said. He was on a watch list of people known as a potential security risk in connection to radical Islamism, the police source added.