not going to address this in some way with their students coming back to class today and maybe look at their own security procedures. the ripple effects are boundless. >> unbelievable. the gunman adam lanza had hundreds of rounds and used multiple high capacity magazines when he went to the school according to police. abc's dan harris has new details about the deadly path lanza took inside the school. >> reporter: after adam lanza shot his way through the glass near the front entrance of the school on friday at around 9:40 a.m., he had choices. lanza could have gone to the right, to the cafeteria, where, according to the hartford newspaper, students were rehearsing a play. straight ahead to the principal's office or left toward the first grade classrooms. he went left and encountered the principal and a school psychologist, who, as we know, local officials say died trying to stop lanza. in the first classroom lanza entered he shot and killed