Gunman Dylan Butler endured years of relentless bullying that had recently engulfed his sister in the leadup to his violent rampage at his rural Iowa high school Thursday, community members said. The 17-year-old was armed with a pump-action shotgun, a small-caliber handgun and a makeshift explosive device when he opened fire at Perry High School at 7:47 a.m., police said. Butler killed a sixth-grader and injured five others, including his principal, before turning the gun on himself. He had plans to kill many more, however — his body was found with the not-yet-detonated improvised explosive device, which cops described as...