Police say a gunman who killed four people in a Manhattan skyscraper before taking his own life claimed to have a brain disease linked to contact sports and was trying to target the National Football

A married father of two with a third child on the way, the 36-year-old was working a New York Police Department-approved private security detail, in uniform, when he and three other people were killed Monday at the Manhattan skyscraper that houses the NFL's headquarters and other corporate offices.

A New York City police officer who was among the four people shot and killed by a gunman during a rampage at a Manhattan office tower will be laid to rest Thursday. Officer Didarul Islam, 36, was fatally shot Monday in a midtown building housing the National Football League’s headquarters.