For those managing such vast traumatic operations, the crucial first step is to drown out, and/or discredit, what eyewitnesses are saying, before the fog of the Official Story covers everything.
Thus it was in Dallas on that deadly day, when so many of the people who'd lined up to cheer the presidential motorcade all turned and ran (heroically) back toward the "grassy knoll," where they had heard the fatal shots come from, and where they spontaneously rushed to catch the gunmen. Those who went on insisting that they'd heard the shots from that direction, and those whose sensory experience was otherwise at odds with the Official Story, were variously silenced, either at the time—by federal agents warning them to keep their mouths shut—or later on. Those who were later silenced often had their testimony altered, if not blacked out entirely, by the FBI and/or Warren Commission, while others weren't so lucky, but were themselves bumped off, to safeguard the integrity of the Official Story.
And thus it was on 9/11, when so many eyewitnesses attested to their sensory experience—of (for example) loud explosions just before the towers were vaporized, and other things that, once the (toxic) dust had settled, we were made not to remember, or to know, as such memories, or knowledge, were now universally laughed off as the imaginings of "9/11 Truthers." (Barry Jennings was one such eyewitness who did not live to testify about his own experience on 9/11.)
And so it was, again, when "COVID" struck, and all of "our free press" were thundering in unison about the "crisis" in the hospitals of New York City—just as they'd done with Lee Harvey Oswald as the "Marxist"/"misfit" who alone had pulled the trigger, and then, again, with those nineteen jihadists who'd (somehow) flown those planes into the towers and the Pentagon. In the first few months of Operation COVID, it was only some eyewitnesses in New York City who took their eyes and ears (and cellphones) out into the streets, discovering that those "overcrowded" hospitals were empty (and that was but the first of countless other revelations that the COVID narrative was actually the biggest of Big Lies).