Inside a three-story Bronx mosque, dozens of Police Department officers sat cross-legged on the floor. They were silent during a somber occasion: the funeral of one of their colleagues, who had been killed in his uniform, just days before.

The slain officer, Didarul Islam, was shot on Monday night after a gunman entered a Park Avenue office building and sprayed bullets across the lobby and then a floor upstairs, killing four people.

The killing of Mr. Islam has ripped through the Police Department with ferocity. But the death had a particular resonance for department’s fast-growing community of Bangladeshi American officers. Mr. Islam immigrated from Bangladesh about 16 years ago.

In the past decade, the number of Bangladeshi Americans who have flocked to the Police Department’s ranks has exploded, marking the latest chapter in the long story of immigrant groups who have found a home — and a foothold in America — in the nation’s largest police department.

“Being police officers, it’s a way to help the New Yorkers, to help the community,” Sergeant Ershadur Siddique, president of the Bangladeshi American Police Association, said in an interview.

“It’s to show that we are part of America, we are part of New York City, and being a police officer in New York City — it’s known in the world that we’re the best in the world — so it brings pride,” he said.