A Nevada man recently traveled to New York City, entered a Manhattan building wearing body armor, carrying an M4 rifle, and fatally shot four people Monday evening, including a New York Police Department officer and injured another,

Wearing body armor and wielding an assault-style rifle, the alleged gunman burst into a Midtown Manhattan office building shooting victims at random.

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