I remember this event pretty well. I was living on 6th Avenue at the time in Midtown and I had just seen a friend off into the Subway before heading downstairs to the family store. Then suddenly, the lights flickered across the street at the parking garage and I turned around to look at the store to see all the lights off.
Immediately, I felt like something was wrong especially since it was the very first time I had ever experienced a blackout in Manhattan. It was surreal as I watched 6th Avenue suddenly become crowded with cars, jammed bumper to bumper due to no working traffic signals. There was one man on 28th Street and 6th Avenue playing the radio out loud from his car stereo with the door open so others could hear. The internet, as I remember it, wasn't like it was today. Mobile phones weren't as connected to the internet as they are today either so really the only way people got information during a complete power outage was from the radio. What a weird time, huh.
Anyway, as night fell on the city, things got eerily silent. A friend of ours stayed with us because there was no way for her to get home and the entire apartment was lit by candlelight and flashlights. I remember walking outside once and only seeing headlights. How eerie not to be able to make out any shapes due to the pitch black darkness!
From what I remember, the city didn't exactly descend into chaos. People were mostly just hanging out waiting for the power to come back on and looting was more of a single event rather than a widespread problem (unlike blackouts that the city has had previously). I do regret not going out and exploring more. I think I was just too scared at that age and not really that keen on going out in the darkness. I know if this were to happen again today that my reaction would be very different.
I've often found myself hoping for a widespread blackout like this again only to see what sort of mischief I could get myself into. I think it'd be "fun" in a weird kind of way.