Gary Clark was a 21-year-old airman at Malmstrom Air Force Base in Great Falls, Montana when John Kennedy was killed. His story here.

On Nov. 22, 1963, a Friday, Clark said the room’s quiet was disturbed by the different-sounding ring of a call from NORAD headquarters. He said he watched as a senior director and his staff, seated at a raised dais, listened and verified the phone message using a cryptographic process.

What happened next, he said he’ll never forget: An officer he recalled as Maj. Van Quill “looked around the room and spotted me sitting by myself.”

The officer, he said, called him crisply by name — “Airman Clark report” — and told Clark he was about to learn something very important, and that he was to go around the room and inform everyone else of what he had heard.

Clark said he can still hear those words, “President Kennedy has been assassinated,” and that Van Quill also told him “assassins” had fired from an overpass. Also, Clark said, the officer told him the U.S. government did not believe the killing was an attack by any foreign country.