MSNBC and NBC News Updated: 1:07 a.m. ET (現地時間) April 17, 2007
BLACKSBURG, Va. - Local, state and federal investigators scoured a university campus in Virginia for clues to what set off the deadliest mass shooting in U.S. history after a gunman shot two people to death in a dormitory Monday morning before making his way to a classroom building where, silently and coolly, he killed 30 more people before turning his weapon on himself, authorities said.