You couldn't miss it.
I think I was driving somewhere near the Board of Education building when I first saw it and took the first picture when I was stopped at a light.
Police and firefighters were gathered on the sidewalk in front of their respective headquarters.
I crossed the tracks and pulled into the municipal lot. I had no idea why the flag was there, but took a few shots because I hadn't seen it there before. I had to be somewhere else and quickly left.
I found out later from irons35 (thanks, Mike) that it was there for the passing funeral cortege of retired Hackensack police officer William Mania.