I believe the incident you're referring to is the Wounded Knee Massacre. It took place at Wounded Knee Creek in South Dakota, USA, on December 29, 1890. A single accidental rifle discharge during a confrontation between U.S. Army soldiers and a group of Lakota Sioux led to a chaotic and tragic event in which scores of Native American men, women, and children were killed by U.S. Army troops. This event marked a dark chapter in the history of U.S. government interactions with Native American tribes.