Hundreds of police officers braved hours of falling rain Thursday to pay their final respects to slain NYPD Officer Brian Mulkeen, who was killed during a life-or-death struggle with a reputed gangster.

Officers from throughout the tri-state area waited for up to three hours to get into the small confines of the Smith, Seaman & Quackenbush Funeral Home in the tiny Orange County village of Monroe, which was essentially shut down by the flood of mourners who came to honor Mulkeen.

Among those paying respect were Mayor Bill de Blasio and NYPD Commissioner James O’Neill. Inside, Mulkeen’s family and fiancee, a cop in the 44th Precinct in the Bronx, patiently greeted mourners.

A sash with the words “Beloved Hero” lay over the cop’s body, which was in an open casket.

“It’s a real tragedy because besides just being a cop he was a good person,” one mourner said.

“He was too young,” said another. “I can’t see him like this.”

A flower arrangement in the shape of a guitar represented his love for music, another was from Fordham University’s track and field team, where he once starred. A third was in the shape of a badge.

Mulkeen, 33, was killed early Sunday at Edenwald Houses in the Bronx during a struggle over his gun with career criminal Antonio Lavance Williams, 27, who was shot in the melee.

He was a star athlete at Fordham before graduating in 2008. Friends said he gave up a chance at a lucrative financial job to become a cop.

Mulkeen and his fiancee lived in Yorktown Heights.

Funeral services are scheduled for Friday.