1978 – Jim Jones led his Peoples Temple to a mass murder–suicide in Jonestown, Guyana, that claimed 918 lives in all.
The Peoples Temple of the Disciples of Christ, commonly shortened to Peoples Temple, was an American new religious movement which existed between 1955 and 1978. Originally founded in Indianapolis, Indiana, by Reverend Jim Jones, the Peoples Temple spread a message that combined elements of Christianity with communist and socialist ideology, with an emphasis on racial equality. After Jones moved the group to California in the 1960s and established several locations throughout the state, including its headquarters in San Francisco, the Temple forged ties with many left-wing political figures and boasted 20,000 members (though 3,000–5,000 are more likely). However, the Temple is best known for the events of November 18, 1978, in Guyana, when 909 people died in a mass murder at its remote settlement, named ‘Jonestown’, as well as the murders of US Congressman Leo Ryan and members of his visiting delegation at the nearby Port Kaituma airstrip. On November 17, 1978, Representative Leo Ryan, who was investigating claims of abuse within the Temple, visited Jonestown, during which visit a number of Temple members expressed a desire to leave with him and, on November 18, they accompanied Ryan to the local airstrip at Port Kaituma. There they were intercepted by self-styled Temple security guards who opened fire on the group, killing Ryan, three journalists, and one of the defectors. That evening, in Jonestown, Jones ordered his congregation to drink a concoction of cyanide-laced, grape-flavoured Flavor Aid. In all, 918 people died, including 276 children.
-Wikipedia