Ostensibly, the electronic magnet lock on our front door should release automatically when there's a blackout, but instead it did the opposite and stayed locked with no way to open the door short of cutting power to the lock at the circuit-breaker level, which we wound up doing, though not before passing fire fighters offered to smash the door with an axe for us (it's made of glass). Though we didn't take them up on their offer, the sight of fire fighters outside our locked-down building brought back poorly timed memories of the movie Quarantine and its Spanish precedent [Rec].
Finally outside, we saw it wasn't just our building but our whole block, St. Marks Avenue between Kingston and Albany, that was having a blackout. Later, from the roof, we could see the smoke billowing out of the blown manhole on the corner of St. Marks Avenue and Albany, and witnessed a sudden tall gout of flame that made the whole block scream and run back inside.
Knowing there was nothing else we could do, Alexa and I went to bed. The power came back on around 2 AM, which is extremely fast for something like this. Thanks, Con Edison! Now please upgrade the grid so it can actually handle an average city block's energy use on the hottest day of the summer, won't you?