The shooter behind a deadly rampage inside an office building in Midtown Manhattan on Monday evening was apparently targeting NFL offices there, New York City Mayor Eric Adams said Tuesday morning.Law enforcement sources say investigators recovered a three-page rambling note from gunman Shane Tamura's wallet in which he referenced the brain disease CTE.

Multiple casualties as gunman opened fire in the lobby of the midtown Manhattan building on Park Avenue that is home to the Blackstone investment firm and other corporations before moving to other floors.

The 27-year-old man who shot and killed four people at a Midtown office building on Monday carried a note in his pocket, police sources told ABC News.