There has only been one similar precedent in NFL history, in November 1963 when President John F. Kennedy was assasinated. The NFL went on with its slate of games, but the AFL postponed its games for a week.
The Bills were slated to play the Boston Patriots in Fenway Park when the news struck about Kennedy’s assasination in Dallas, and owner Ralph Wilson was the first AFL owner to order the cancellation of one of four games that weekend.