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.

Shane Tamura, the 27-year-old man who shot and killed four people inside a Midtown office building, didn’t show up for his shift as a Las Vegas casino security guard on Sunday, according to authorities.

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