Carabinieri police said Monday that their ROS special-operations unit have arrested a 17-year-old boy residing in Perugia who was allegedly planning a school massacre.     Investigators believe the boy was working to make weapons and chemical devices to use in the attack.     The suspect followed a Telegram group with on content on the supposed superiority of the "Aryan race".     He faces criminal charges for the possession of materials for terrorist purposes and for propaganda and incitement