Dhaka, July 29 -- A gunman armed with a rifle opened fire inside a New York City office building on Monday, killing four people - including an off-duty NYPD officer - and injuring a fifth, before dying by suicide.

Police Commissioner Jessica Tisch said that one of the victims was Didarul Islam, 36, a Bangladeshi immigrant who had been with the NYPD for three and a half years.

"He was doing the job that we asked him to do. He put himself in harm's way. He made the ultimate sacrifice," Tisch said. "He died as he lived. A hero."

One killed another injured in University of New Mexico dorm shooting

Police identified the gunman as Shane Tamura, of Las Vegas, and said he killed himself. He had a 'documented mental health history,' but the mo...