On May 1, 1970, the night after President Nixon announced the U.S. invasion of Cambodia, I saw the movie Zabriskie Point. In a scene about a fictional campus confrontation, a policeman shot a college student. How unreal that seemed to me, a student at Kent State University in Ohio and a nonprotester. Later that evening, anger over Nixon’s latest escalation of the Vietnam War boiled over in downtown Kent. Protesters threw rocks at cars and broke store windows.

The outburst prompted Kent Mayor Leroy Satrom to declare a state of emergency the next day. Gov. Jim Rhodes ordered in the National Guard to prevent further violence. Shortly before the Guard arrived that night, I was a curious bystander as antiwar protesters surrounded the university’s old wood ROTC building. It was set afire. Ammunition exploded inside as the building burned. Looking up, I saw flames reaching high, bits of floating wood and hovering helicopters shining spotlights at us on the ground.

All was calm the next day when I walked past those smoldering ruins and through Prentice Gate, the main entrance to the campus. Rifle-toting guardsmen stood on rooftops, their armored vehicles below; one detachment marched toward the library. I went inside the library to view that end of campus, and from an open window watched a National Guard officer question a male student. His answer? Not quick enough. I heard the thud of the baton hit him on his back.

Noon on Monday, May 4, found me at a student rally at the Commons to protest the Guard’s presence. Though we were told to disperse, students kept showing up. The guardsmen used tear gas, to little effect, the winds blowing it away from us. Next, the Guard affixed bayonets to their rifles, forcing us to retreat over a small hill toward a fenced football practice field. As we retreated, the Guard sprayed us with pepper fog, and I felt a horrible tight pain in my chest. Then, I heard small pops, almost like firecrackers, 67 gunshots in all, it was later determined.

On that evening’s news, the world heard a body count of four dead and nine wounded, not in Vietnam but at Kent State in central Ohio.

Before the events of May 4, 1970, my political awareness hadn’t really taken shape at all. That day it all changed when I became a witness of humankind at its worst. In the years since, I have tried to remain optimistic, finding marriage, fatherhood and job stability. I have learned to empathize in the workplace, take more interest in other cultures and work to elect political candidates who seem sympathetic to my views. My wife and I will return to Kent State on May 4 to commemorate the tragedy and to remember those few days of my transition from teenager to adult 40 years ago.

Ralph Spielman lives in New York City