On this date in 1970, Ohio soldiers shot students of Kent State University who protested the U.S.-Vietnam War, killing four students and wounding nine others.

On this date in 1960, the Soviet Union shot down an American U-2 reconnaissance airplane and captured its pilot, Francis Powers.

On this date in 1986, the worst nuclear reactor accident occurred in Chernobyl in the Soviet Union. An explosion and fire sent radioactivity into the air. At least 31 Soviets died immediately, and many more persons died from radiation poisoning.