Four people were killed and a fifth was injured in a mass shooting at a Midtown Manhattan office building on Monday.

The police officer who was killed when a gunman opened fire in a Manhattan building was a dedicated father who was working a second job as a security guard.

Family, friends, and colleagues are mourning an NYPD officer who was killed in a mass shooting in a Manhattan building Monday evening. Officer Didarul Islam, 36, was on duty working a private security detail when he was fatally shot in the lobby at 365 Park Ave.