Tlatelolco massacre
Following a summer of increasingly large demonstrations protesting against the 1968 Olympics held in Mexico City, the Mexican Armed Forces opened fire on 2 October 1968 on unarmed civilians, killing an undetermined number, in the hundreds. It occurred in the Plaza de las Tres Culturas in the Tlatelolco section of Mexico City. The events are considered part of the Mexican Dirty War, when the US-backed PRI regime violently repressed political and social opposition. The massacre occurred 10 days before the opening ceremony of the Olympics, which were carried out normally.