Howard Cosell annouced it during Monday Night Football.
Cosell: Yes, we have to say it. Remember, this is just a football game, no matter who wins or loses. An unspeakable tragedy confirmed to us by ABC News in New York City: John Lennon, outside of his apartment building on the West Side of New York City – the most famous, perhaps, of all of the Beatles – shot twice in the back, rushed to Roosevelt Hospital, dead on arrival. Hard to go back to the game after that newsflash, which, in duty-bound, we have to take. Frank?
Gifford: (after a pause) Indeed, it is.[[56]]