AdvertisementSchools Have Become More Secure Since Columbine, Experts SayDecember 14, 2012Scott NeumanfacebookEmailPolice gather at the east entrance of Columbine High School in Littleton, Colo., on April 20, 1999. School security has improved markedly since the Columbine shooting, experts say, but there still are problems. (AFP/Getty Images)
