From Cambodia to Kent State

After President Nixon address on Cambodia protests flared up, the most violent is from an university campus in Ohio. The following is an excerpt from a text in internet:

The Kent State shootings—also known as the May 4 massacre or Kent State massacre occurred at Kent State University in the city of Kent, Ohio, and involved the shooting of unarmed college students by members of the Ohio National Guard on Monday, May 4, 1970. The guardsmen fired 67 rounds over a period of 13 seconds, killing four students and wounding nine others, one of whom suffered permanent paralysis.
Some of the students who were shot had been protesting against the American invasion of Cambodia, which President Richard Nixon announced in a television address on April 30. Other students who were shot had been walking nearby or observing the protest from a distance.
There was a significant national response to the shootings: hundreds of universities, colleges, and high schools closed throughout the United States due to a student strike of four million students, and the event further affected the public opinion—at an already socially contentious time—over the role of the United States in the Vietnam War.

The US intervention had led to more bombing in Cambodia and intensification of communist Vietnamese fighting alongside with the Khmer Rouges against the inferior forces of the Khmer Republic. The Khmer Rouge won on April 17, 1975.