I turn every computer I can get my hands on into a time machine. While I have a generally upbeat take on history, like
Caps once said to me - "I've experienced both the good and the bad". This is an example.
On December 8th, 1980 the first announcement, that I know of, on John Lennon's death was Howard Cosell on ABC's "Monday Night Football". Cosell was handed a news bulletin while the football game was in progress. His first instinct was to withhold the news until the game was finished but his co-host Frank Gifford told him "this news must not wait, you have to tell them Howard".
Howard Cosell had the difficult task of telling viewers of Lennon's death while the New England Patriots were attempting a field goal against the Miami Dolphins. Later in the game, Cosell made the announcement of Lennon's death a second time for viewers that missed his first announcement.
News Flash - Monday Night Football...
And here's the Nightline broadcast mentioned by Howard Cosell in the above video link:
Lynn Sherr's report for Nightline...