Follow along for live updates on the New York City shooting, where police investigate motive after five people, including the gunman, were killed in the Monday shooting.

Officials say a man carrying a rifle killed four people at a New York City office tower. The shooting took place Monday afternoon at a midtown Manhattan office building that houses finance companies and the NFL headquarters.

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.