The most prolonged and intense phase of the 1968 Mexico City Terrorist Attacks began in the afternoon of October 22nd, when a highly trained Children of God assault team stormed the Olympic Village, taking hundreds of athletes, coaches, and officials hostage. The attackers disguised themselves as Olympic staff, slipping past security with concealed weapons and quickly securing key dormitories. Within minutes, entire national teams were held at gunpoint, and several athletes who resisted were executed on the spot. The terrorists' demands were clear: the immediate release of all imprisoned left-wing militants in Mexico and the withdrawal of the country from NATO.
The Mexican military and police, already spread thin after the Zócalo Bombings and Televisa Massacre, mobilised to surround the compound, but were reluctant to storm it outright, fearing a massacre of hostages. Meanwhile, a United Nations (UN) Security Council emergency meeting was called in New York, with the world's powers offering the assistance of their special forces. On the second day of the siege, many of these special forces were concentrated in Mexico City as the UN Counter-Terrorist Team. At the time it was the most impressive act of international coordination since the Black Sand War; American Green Berets, Soviet Spetsnaz, German Jägerkommandos, French Paracommandos, British S.A.S., Chinese "Southblades" and even Oceanykan "Black Bunyips" were put together with hand-picked soldiers from the Brigada de Fusileros Paracaidistas (Paratrooper Brigade) and, coordinating with the Secretaría de la Defensa Nacional (SEDENA) for exterior security, prepared to breach in. As tensions escalated, the terrorists began executing hostages, choosing them at random and broadcasting the killings through hijacked Olympic communication channels.
On October 25th, after many gruelling hours, the decision was made to storm the Olympic Village. The UN Counter-Terrorist Team opened up with explosive charges on the compound's walls, flooded the village with tear gas, and broke in. The ensuing firefight was one of the deadliest hostage rescue operations in history, with both hostages and attackers caught in brutal crossfire. By the time the dust settled, there were over 200 dead, including all but one of the attackers and 7 operators. The sole surviving terrorist, captured alive, was later interrogated by the CIA using cutting-edge techniques developed in Project MKUltra, claiming that him and the other "Children of God" had been trained by the Moonlight Commandos.
The UN Counter-Terrorist Team was disbanded as the Siege ended. It was, however, the direct predecessor of the modern United Nations Counter-Strike Force (UN COSFOR), a multinational unit formed specifically to deal with high-profile terrorist attacks like those of Mexico City.