Police officers enter the building after a shooting at Reynolds High School in Troutdale, Oregon June 10, 2014. A gunman walked into the Oregon high school with a rifle and shot a student to death on Tuesday before he was later found dead, in the third outbreak of gun violence to shake a U.S. high school or college campus in less than three weeks. REUTERS/Steve Dipaola (UNITED STATES - Tags: CRIME LAW EDUCATION)