A funeral was held Thursday for NYPD Det. Didarul Islam, one of the victims killed in Monday's shooting at a Midtown office building.

Islam came to New York City from his native Bangladesh when he was 20 years old, with "the promise of a better life," NYPD Commissioner Jessica Tisch said.

Roughly 15,000 mourners gathered for the funeral of NYPD Officer Didarul Islam, who was killed in an office building shooting while working an off-duty security detail.