The Kent State Massacre:
National Guardsmen fire on a crowd of students protesting the Vietnam War and the American invasion of Cambodia at Kent State University, killing four students and wounding nine more - paralyzing one for life. Earlier protests had turned to rioting, which had first spurred the calling of the National Guard to the University.
The shooting itself lasted only 13 seconds, in which 67 bullets were fired at close range.
May 4, 1970 - 42 years ago today.