Twelve years after moving to the United States from Bangladesh, Didarul Islam sought to join the ranks of the nation's largest police department because he "got inspired" by the "blanket" of protection the NYPD provided to his community, according to an essay he wrote as part of his police academy application.

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.

But on Monday evening, Islam, who was regularly assigned to the 47th Precinct in the Bronx, was gunned down by an armed suspect identified as Shane Tamura, as the officer was dong a paid detail shift at 34d Park Avenue, a skyscraper home to several large New York City corporations.

New York's mayor says the father of two was doing what he did best and protecting New Yorkers when he was shot dead on Monday evening.

Thousands of police officers from across the country joined New York’s South Asian community Thursday to mourn Didarul Islam, the NYPD officer slain in a mass shooting at a Manhattan office building earlier this week.