A note found in the gunman's wallet was critical of the NFL and mentioned CTE. The 27-year-old wrote, “Study my brain please. I’m sorry."

Players and coaches around the NFL learned Tuesday that the target was the NFL itself, Mayor Eric Adams said, with the shooter picking the wrong elevator bank and getting off on a different floor.

The man who opened fire in a Midtown Manhattan office building, killing four people and wounding a fifth, appeared to be targeting the NFL headquarters and had a note claiming he suffered from CTE, police sources told ABC News.