Didarul Islam, a 36-year-old NYPD officer, was off duty and working a security job when he was fatally shot by a gunman who opened fire at the 345 Park Avenue office building on Monday.

There were 23 shell casings and 13 bullet fragments recovered from the lobby of 345 Park Avenue and 24 spent shell casings on the 33rd floor, police said.

A New York City police officer and three other people were killed in a shooting in Midtown Manhattan on Monday evening, police confirmed at a late-night news conference.