No motive has been announced. A suicide note was found expressing grievances with the NFL and saying Tamura suffered from CTE, a source said. Follow for live updates.

Investigators are examining why the gunman who killed four people before taking his own life at a New York City office tower targeted the National Football League and whether he suffered from a brain disease.

As for security, badges and sign-in lists for visitors became standard fare in New York office buildings after the Sept. 11 attacks nearly a quarter-century ago. Many buildings installed turnstiles between guard desks and building elevators. In recent months, some buildings had stepped up their precautions even more because of the war in Gaza.