Final answer:
The Ohio National Guard fired at demonstrators without an order to do so at Kent State University in Ohio on May 4th, 1970.
Step-by-step explanation:
The Ohio National Guard fired at demonstrators without an order to do so at Kent State University in Ohio on May 4th, 1970. During a protest, the National Guard troops approached the students, forced them to retreat, and then unexpectedly turned and began firing, resulting in the death of four students and injury of nine others.