Officials said the gunman fatally shot himself after his attack, which set off a chaotic scene that rippled out into the heart of Manhattan during rush hour.

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. Islam, a Bangladeshi immigrant who joined the NYPD four years ago, is survived by his wife, who is eight months pregnant, and two young sons.

NEW YORK -- A 27-year-old man wearing body armor and carrying an M4 assault rifle shot and killed four people, including off-duty New York Police Department Officer Didarul Islam, who was working security in a Midtown Manhattan office building, officials said during a press conference Monday evening.