Oh, the Boston Massacre from the US War of Independance. I had the Boston Marathon bombing in mind, and even then I was wrong. "Only" 3 fatalities (though hundreds of injuried)
It's hard to say communism never spread to South America when any attempt at communism was brutally overthrown through CIA-backed coups. Even Salvador Allende was supported by Chilean Communists and is considered a Marxist. I would hardly say that counts as "never spreading".