Police have identified the man who they say entered a Midtown Manhattan office building wearing body armor and opened fire, killing four people with a high-powered rifle, as Shane Devon Tamura.

The gunman, who said in a note he believed he had CTE, targeted skyscraper that houses the NFL's headquarters.

Shane Devon Tamura, the man identified as the gunman who killed four people in a deadly shooting at a midtown Manhattan office building that houses the NFL 's headquarters, was once a standout high school football player.