be used against you in a court of law. do you understand that right, sir? yes, i do. reporter: wearing a face mask and handcuffs, 15-year-old ethan crumbley sat motionless as he was arraigned on 24 felony counts, including terrorism and first degree murder his parents also attended virtually. there are facts leading up to the shooting that suggest this was not just an impulsive act. school shooting at oxford high school. reporter: on tuesday, investigators say the sophomore came out of a rest room at oxford high school, and fired at least 30 round fra semiautomatic handgun. hours earlier, authorities say crumbly and his parents met with school officials over behavior concerns. sheriff s office. it s safe to come out. reporter: cell phone video shows terrified students barricaded behind a locked door before running to safety. go!