A note found in the gunman's wallet was critical of the NFL and mentioned CTE. The 27-year-old wrote, “Study my brain please. I’m sorry."

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.

An NFL employee was seriously injured during the mass shooting at the Manhattan office tower that houses the league’s headquarters.