On April 30th President Nixon announced the invasion of Cambodia. The invasion unleashed protests on campuses throughout the United States. Demonstrations were particularly boisterous at Kent State University. The protest spread from the campus to the downtown. On May 1st, rioters in town threw bottles at police. The mayor of the city requested from the governor National Guard troops to help keep the peace.

In the evening of May 2nd, the ROTC building on the camps was set on fire as demonstrations continued. Ohio Governor Jim Rhodes had a press conference where he stated:

We've seen here at the city of Kent especially, probably the most vicious form of campus-oriented violence yet perpetrated by dissident groups. They make definite plans of burning, destroying, and throwing rocks at police and at the National Guard and the Highway Patrol. This is when we're going to use every part of the law enforcement agency of Ohio to drive them out of Kent. We are going to eradicate the problem. We're not going to treat the symptoms. And these people just move from one campus to the other and terrorize the community. They're worse than the brown shirts and the communist element and also the night riders and the vigilantes. They're the worst type of people that we harbor in America. Now I want to say this. They are not going to take over [the] campus. I think that we're up against the strongest, well-trained, militant, revolutionary group that has ever assembled in America.

On May 4th a protest was planned at the center of the University. The National Guard demanded that the protesters disperse. The protesters refused. The National Guard began to use tear gas on the protesters. Because of the winds, the tear gas was not effective. The guardsman then advanced with fixed bayonets. The students retreated, and the guardsmen followed. Most of the protesters had disbursed, but some remained taunted the National Guard and throwing things at them. They chanted “ pigs off the campus.” Suddenly one guard sergeant used his pistol and fired at the protesters, he was followed by 28 additional soldiers who fired 67 rounds. The rounds killed four protesters and wounded nine. The National Guard claimed that they had been fired upon. Two of those killed Allison Krause and Jefferey Miller had participated in the demonstrations while two Sandra Scheuaer and William Knox Schroeder had merely been walking two their next class.

Student strikes broke out throughout the United States. Four hundred fifty campuses were forced to close for a few days. The National Guard troops who fired were never prosecuted. The event cemented the great divide that the Vietnam War had created in the American society.