By Amanda Musa, Rebekah Riess, Jessie Yeung, CNN (CNN) — A New York police officer, a “beloved” security guard, a young Cornell graduate and a senior executive with investment firm Blackstone were killed Monday when a lone gunman stormed a sprawling office tower in Midtown Manhattan and opened fire. The shooter then killed himself, ending … Continue reading An NYPD officer, security guard, Blackstone exec and Cornell grad were killed in the Manhattan shooting. Here’s what we know