Kent University students held a demonstration after President Nixon appeared to go back on his election promise to withdraw from Vietnam. The protests started the previous Friday with the intention to gather again at noon on Monday, 4 May 1970.
That weekend was marked by fires and fighting and so the Ohio National Guard was called. Rocks were thrown at them on the Monday.
For reasons still unclear to this day, 28 of the 70 Guardsman fired into the air, into the ground, and into the students.