I remember the music they were playing on one Top 40 station on Monday, November 25, 1963. The station announced that "now is not the time to return to regular programming" and resumed playing what some people described as "a dirge".
A couple of years ago, Michael DelGiorno interviewed his father, Bob DelGiorno, on WWTN Nashville. He described the Kennedy assassination as the most significant time in his career. When he heard about the shooting, he dropped the other local Top 40 format immediately at WTAC, and proceeded to direct all day News coverage, a format he had never done before. Bob said the next most significant time in his career was Hurricane Katrina, where he reprised a similar all day News format on WWL, serving as a clearinghouse for emergency communications there for Days, when nearly all other communications were knocked out, including landline and cell phone. So all news, and "a dirge" were two formats used under these circumstances.