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.

Four people were killed and a fifth was injured in a mass shooting at a Midtown Manhattan office building on Monday. Among those killed was an officer who was a dad of two with a third on the way.

The Manhattan office building shooting victims include NYPD Officer Didarul Islam, Blackstone executive Wesley LePatner and security guard Aland Etienne.