For 10  points, identify this May 4, 1970 incident in which the Ohio National Guard fired into a crowd of  unarmed protesters at an Ohio university.
One famous depiction of this event was captured by John Filo, and most prominently featured  Mary Ann Vecchio and Jeffrey Miller. Spurred in part by Governor James Rhodes describing  participants of a protest as "un-American", this event saw 67 shots fired, which killed 4 people  and injured 9 others, some of whom had been protesting the U.S. invasion of Cambodia. For 10  points, identify this May 4, 1970 incident in which the Ohio National Guard fired into a crowd of  unarmed protesters at an Ohio university.
One famous depiction of this event was captured by John Filo, and most prominently featured  Mary Ann Vecchio and Jeffrey Miller.
Kent State massacre