The studios at Fox News, CNN and MSNBC filled with anchors and commentators, waiting for Attorney General William P. Barr to make news on Sunday afternoon with the release of a letter summarizing the findings of the special counsel, Robert S. Mueller III.

As the cable teams assembled, NBC News prepared to interrupt a golf tournament and ABC News got ready to break into coverage of a professional video-game contest.

NBC was the first broadcast network to provide details of Mr. Barr’s four-page summary of Mr. Mueller’s far lengthier and still unpublished report. The network’s justice correspondent, Pete Williams, stood before the Justice Department headquarters in Washington and simply read aloud from the attorney general’s letter to Congress.

After he was through, Kate Snow, the NBC anchor on duty, said, “Some of what you just read cold on the air is a lot of legalese.”