As the disaster of yet another school shooting hits, some parents are faced with a brutal fact: that their child was the one pulling the trigger. Three parents share their stories. Jeff Williams is the father of Andy, who in 2001, at the age of 15, shot and killed two classmates and wounded 13 other students. Clarence Elliot's son Nicholas shot and killed his teacher and wounded another in 1988. Sue Klebold's son Dylan was one of the two teenagers behind the Columbine High School massacre in 1999, one of the deadliest school shootings in history.