(CNN) Police say the fatal shooting of a New York Police Department officer was the result of friendly fire.

"This is a tragic case of friendly fire, but make no mistake, we lost a life of a courageous public servant solely due to a violent criminal who put the lives of the police and all the people we serve in jeopardy," New York Police Department Commissioner James O'Neill said Monday.

Brian Mulkeen, a 33-year-old member of The Bronx Anti-Crime Unit, was investigating gang activity, including recent shootings with two other officers at about 12:30 a.m. Sunday, NYPD said.

NYPD officer Brian Mulkeen was fatally shot Sunday.

The officers got out of their vehicle to question a man, who then fled, and the officers gave chase. As the officers tried to apprehend the suspect, a violent struggle on the ground began, NYPD Chief of Department Terence Monahan previously announced.

In body-worn camera, Mulkeen can be heard yelling "He's reaching for it! He's reaching for it!" Monahan said earlier.

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