The killings at Kent State

Four students died and nine others were wounded on May 4, 1970, when members of the Ohio National Guard opened fire on students protesting the Vietnam War at Kent State University in Ohio. In this Pulitzer Prize-winning photo, taken by Kent State photojournalism student John Filo, Mary Ann Vecchio can be seen screaming as she kneels by the body of a slain student. Watch "Witnessed: The Killings at Kent State," a CNN Special Report, on Sunday at 7 p.m. ET.

Four students died and nine others were wounded on May 4, 1970, when members of the Ohio National Guard opened fire on students protesting the Vietnam War at Kent State University in Ohio. In this Pulitzer Prize-winning photo, taken by Kent State photojournalism student John Filo, Mary Ann Vecchio can be seen screaming as she kneels by the body of a slain student. Watch "Witnessed: The Killings at Kent State," a CNN Special Report, on Sunday at 7 p.m. ET.