The gunman who killed four people, including an NYPD officer, reportedly had a grievance against the NFL and blamed football for issues with CTE.

Investigators believe Shane Tamura, of Las Vegas, was trying to get to the NFL offices after shooting several people Monday in the building’s lobby but accidentally entered the wrong set of elevator banks,

The shooter who killed four including Blackstone executive and NYPD officer left suicide note indicating he believed he had CTE from brain trauma, Adams says