By Roseanne Tellez

(CBS) — There were angry words and then gunfire on the city’s Northwest side.

Chicago police say an off-duty officer fired back at a group of men who fired at him first on Sunday night.

The incident went down on a busy street during the dinner hour, and as CBS 2’s Roseanne Tellez discovered, a surveillance camera was rolling.

A surveillance camera along Kedzie avenue in Albany Park shows a dark car pulling into McDonald’s, past some pedestrians. Police say the vehicle’s occupants instigated a verbal confrontation.

Video shows the car coming back around and stopping in the middle of the street. Police say they brandished a gun and fired.

Figures on the sidewalk crouch down. One appears to fire a gun toward the stopped car, which stays put, even as another driver in a silver car slams his car into reverse and backs away.

Police confirm one of the pedestrians was an off-duty Chicago police sergeant.

Authorities say a man involved in the confrontation “self-transported” to a nearby hospital with a gunshot wound to the head.

Officers went to the hospital and turned up a weapon.

Police say their investigation confirms the wounded male was involved in the Kedzie shooting. And that there’s evidence that the gun found had been fired.

All we know about the off duty sergeant is that he was assigned to the Town Hall district, but is now on routine administrative duties as the Independent Police Review Authority investigates.

Neither the sergeant nor his companions were hit by any gunfire.