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 was the 27-year-old man living in Las Vegas who fatally shot at least four people in a mass shooting at 345 Park Avenue in New York City on July 28. Here's what to know about the N.