Shane Tamura, the Park Ave. gunman who killed an NYPD officer and three others before taking his own life, left behind a suicide note saying he suffered from CTE, a brain injury often linked to playing football, and was targeting the NFL — but took the wrong elevator, officials said Tuesday.

New York City Mayor Eric Adams said on “Morning Joe” on MSNBC there is belief Tamura may have been targeting the NFL office in the building.

The alleged gunman was identified as 27-year-old Shane Tamura, of Nevada. Police said the motive for the shooting remains under investigation and investigators are working to understand why the suspect targeted the commercial building.