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.

The gunman who shot and killed four people at a midtown Manhattan building Monday before killing himself bought the murder weapon for $1,400 from his boss at the Las Vegas casino where he worked security, NYPD officials said Wednesday.