In 1970, the United States was fighting a war in Vietnam. Many Americans believed the war was wrong. College students across the country held protests to demand that the government bring soldiers home. On May 4, 1970, students at Kent State University in Ohio gathered on campus. They were angry because President Nixon had just sent troops into Cambodia, a neighboring country. The Ohio governor called in the National Guard to keep order. Tensions were high, and some students threw rocks at the guards. The guardsmen wore gas masks and carried rifles. Then something terrible happened. The guardsmen fired their weapons into the crowd, and four students were killed. Nine more were wounded. The shootings shocked the nation. Many people could not believe that American soldiers had fired on American students. Over four million students went on strike across the country. The event was a turning point in the Vietnam War. Photographs of the tragedy appeared on every newspaper's front page, turning more Americans against the war.