If I had to guess, they still had everything "on". Most systems, especially big beasts like your fridge, have a large initial draw. If everything suddenly came on, the draw might have been more than their wiring could manage. Again, that's just a guess.

But it is the reason why SOP here is if we loose power, turn off every breaker except for the one to the overhead lights in the living room and the outside lights. Which get turned on- when they are on, throw the other breakers one at a time.