NEW YORK (AP) — Police gathered in deep formation in front of a mosque on Thursday to honor a fellow officer, one of the victims in a gunman’s violent spree at a New York City office tower.

With officers positioned for security on the rooftops surrounding the Bronx mosque, fire trucks used their ladders to display a large American flag over a nearby street before the services for Officer Didarul Islam, 36. A flatbed truck showcased a digital billboard with his photos and a commemorative message from his union.

Officers filed in for a viewing, to be followed by family, friends and dignitaries.

Islam was on an officially sanctioned private security assignment, in uniform, when he was shot and killed Monday in a midtown Manhattan building that hosts the National Football League’s headquarters. Also killed were a security guard, a real estate company worker, and an executive from an investment firm. The gunman injured a fifth individual, an NFL employee, before taking his own life.

A Bangladeshi immigrant, Islam was carving out a career in the nation’s largest police force. Initially serving as a school safety agent, he advanced to becoming a patrol officer less than four years ago.

“He was fulfilling the mission we set for him. He courageously faced danger. He paid the ultimate price,” Police Commissioner Jessica Tisch remarked following the tragedy. “He lived and died as a hero.”

Islam was stationed at a precinct in the Bronx, where he resided with his wife and two young sons. His wife is expecting their third child shortly.

After Thursday’s viewings and a prayer service at the Parkchester Jame Masjid, Islam will be buried at a cemetery in Totowa, New Jersey.

Another victim, Julia Hyman, was buried following an emotional service Wednesday at a Manhattan synagogue. The 27-year-old Cornell University graduate had worked for Rudin Management, which owns the building.

Funeral arrangements for the two others killed, security guard Aland Etienne and investment firm executive Wesley LePatner, have not been made public.

Police identified the gunman as Shane Tamura, a 27-year old former high school football player who most recently worked in a Las Vegas casino’s surveillance department. Authorities say he drove to Manhattan because he believed he had a brain disease linked to contact sports and accused the NFL of hiding the dangers of playing football.

Officials said he was heading for the NFL’s office but took the wrong elevator and went by mistake to another floor that housed Rudin Management’s offices. The wounded NFL employee happened to be in the lobby when Tamura was firing there.

Police said Tamura had a history of mental illness, but they haven’t elaborated other than to say they found psychiatric medication prescribed to him at his residence in Las Vegas.

___

Associated Press reporter Jennifer Peltz contributed.