President René Barrientos believed that the start of a new guerrilla resistance to his dictatorship was brewing among the mining communities, inspired by Che Guevara's small force which was operating in Bolivia at the time.
[3] The assembled miners and families celebrated the festival of the longest night of 23 to 24 June with bonfires, firecrackers and dynamite as well as traditional foods and beverages, not knowing that units of the elite Rangers and Camacho regiments of Oruro had already surrounded them.
[4] It all began when the mining families were returning home to sleep after celebrating the winter solstice around bonfires, where they had danced and sung to the rhythm of cuecas and huayños, accompanied by alcohol-spiked punches, traditional foods, coca, cigarettes, bursts of dynamite and firecrackers.
As this was going on among the civilian population of Llallagua and the mining camps of Siglo XX (20th Century), troops from the Ranger and Camacho regiments, which just hours before had surrounded them under cover of night, opened fire from every direction, with a toll of some twenty killed and seventy wounded amid stabs of cold and the whistling of the wind.
There they murdered union leader Rosendo García Maismann, who, barricaded behind a window, defended the radio station with an old rifle in hand.A 1971 film documentary "The Night of San Juan" (original title "El coraje del pueblo") was directed by Jorge Sanjinés based on a script by Óscar Soria Gamarra [es].