New York City is mourning NYPD Officer Didarul Islam and three other people killed in Monday's shooting inside an office building at 345 Park Ave.

Police lined the streets of New York City to pay their respects to fellow officer Didarul Islam, who was among the four victims of a gunman’s rampage Monday at a Manhattan office tower.

The New York police officer killed in a mass shooting in a Manhattan skyscraper on Monday was an immigrant who left behind a pregnant wife, two young sons and distraught parents, while friends and officials in Bangladesh and the United States described him as a hero.