NEW YORK (WPIX) – According to Mayor Eric Adams, a note discovered with the Manhattan shooter who killed four people indicated that he had experienced a brain injury.

Adams said that 27-year-old Shane Tamura blamed the NFL for his injury.

Adams stated, “He was not affiliated with the NFL. It seems he was accusing the NFL of causing his CTE… He then ended his own life by shooting himself in the chest. It seems he wanted to keep his brain intact for research purposes.”

Authorities reported that Tamura shot and killed three individuals in the building’s lobby, including New York Police Department Officer Didarul Islam, who was on a private assignment. Another casualty was a security guard, as well as Wesley LePatner, an executive from Blackstone. An NFL employee present in the lobby was also wounded and is receiving medical care for the injuries, officials confirmed.

Tamura, who intended to head to the NFL offices, then accidentally went into the wrong elevator and headed up to Rudin Management, Adams said.

The fallen security guard, who was attempting to hide behind a desk, might have disabled the elevators to stop Tamura from reaching higher floors, as per Adams’s remarks.

In the Rudin Management offices, police reported that Tamura fatally shot another person before turning the gun on himself. Authorities confirmed his death was due to a self-inflicted gunshot wound.

The gunman did not appear to contact the NFL before the shooting, according to Adams.