A heavily armed 14-year-old boy shoots and kills his school principal inside a crowded junior high cafeteria in Red Lion, Pa., then kills himself. Authorities say there were no known problems between the boy, who did not have a record of disciplinary problems, and the principal, Eugene Segro. The same school district was the site of a machete attack on a kindergarten class that injured a principal, two teachers and 11 of the 23 pupils in 2001.