Snipers fire upon left-wing Peronists in Buenos Aires, Argentina, in what is known as the Ezeiza massacre. At least 13 are killed and more than 300 are injured.

The Ezeiza massacre (Spanish pronunciation: [esejsa]) took place on June 20, 1973, at Puente 12, the intersection of General Ricchieri freeway (the Ezeiza Airport access) and Camino de Cintura (provincial route 4), some 10 km distant from Ezeiza International Airport in Buenos Aires, Argentina.

Peronist masses, including many young people, had gathered there to acclaim Juan Pern's definitive return from an 18-year exile in Spain. The police estimated three and a half million people had gathered at the airport. In his plane, Pern was accompanied by president Hctor Cmpora, a representative of the Peronists' left wing, who had come to power on May 25, 1973, amid popular euphoria and a period of political turmoil. Cmpora was opposed to the Peronist right wing, declaring during his first speech that "the spilled blood will not be negotiated".From Pern's platform, camouflaged snipers from the right-wing of Peronism opened fire on the crowd. The left-wing Peronist Youth and the Montoneros were targeted and trapped. At least 13 bodies were subsequently identified, and 365 were injured during the massacre.According to Clarn newspaper, the real number is thought to be much higher. No official investigation was ever performed to confirm these higher estimates.

A sniper is a military/paramilitary marksman who engages targets from positions of concealment or at distances exceeding the target's detection capabilities. Snipers generally have specialized training and are equipped with high-precision rifles and high-magnification optics, and often also serve as scouts/observers feeding tactical information back to their units or command headquarters.

In addition to long-range and high-grade marksmanship, military snipers are trained in a variety of special operation techniques: detection, stalking, target range estimation methods, camouflage, field craft, infiltration, special reconnaissance and observation, surveillance and target acquisition.