This is one scenario that is not really explained as to how it happened or why, but the story centers around something much more meaningful to us as readers, and it's the extent to which we have become dependent on electricity, and not only for recreational purposes such as watching tv or surfing the internet, nor for work related endeavors like using a computer for almost everything we do, but on a more basic level, such as the need to power the pumps that deliver water to our houses, or maintaining refrigerated foods so they don't spoil, or pumping gas into our cars, and how we are no longer able to move freely without a car, how we dread having to carry our groceries for a little over a mile.
But the really interesting thing in this book is the way it portrays the response of people to loosing such commodities of modern life, such comforts, tools and aides to everyday life. The first group I'll address is not the main character group of the story, but the one we see the least of but that has the greatest impact in the events of the story, and these are what the characters call MZB (Mutant Zombi Bikers); they were once your everyday gang-bangers, hoodlums, and criminals of all kinds. They are the ones most likely to resort to violence first, and already have acces to a large and fairly organized group of people, armed and ready to use those weapons against their former neighbors. These groups are a fairly common occurrence in apocalyptic and post-apocalyptic stories, and it's not hard to imagine them.
The second group of people is comprised of those who refuse to believe that the world has changed as dramatically as it has, and have faith that the government, or some other higher authority than themselves will come in and fix everything. They are the ones who refuse to leave their home until it is either too late, or it's evident that they have no other option. This is the case with the priest who refuses to leave his parish, or Ralph, the lawyer who only leaves when his house is attacked. They are the majority of the people, but in the novel they are seen only in relation with the third group of people.
This last group is the one in which people are quick to realize that things have changed, and it can be divided into two extra segments. The first one is represented by the ones who went to live in Mr. Davis's ranch; people who had been preparing for an apocalyptic scenario since before The Burst came about. Initially they are presented as the best alternative in a changing world, until Mark Turner and his family look under the veneer of security, they find that the despotic rule of Mr. Davis, with his attitude of "my way or the highway", is not what they want in times of crisis, and then the story shows us that this group has fallen prey to an overconfidence that proves to be their undoing; they feel so superior to everyone else that they do not acknowledge the situation to be above what they anticipated, which in the end leads to their downfall.
The second segment, and the most important in the novel for it being the one with the main characters in it, is also aware of the change in society, but they see it not as a static change, but realize that the situation is dynamic, and you have to adapt to it, but also that it cannot be done on your own, and it is necessary to band together with your neighbors and work in adapting to the new realities facing society every day. This is the group that shows us that civilization as we know it will not really end in a day, but rather it will transform itself into something different over the course of time, and some people will adapt better to the change than others.
Unlike other survival and preparedness stories "Lights Out" deals with regular people, not "survivalist nuts" as they are called by Mark Turner in the story; people who have been storing and hoarding food and resources in case some disaster happens; people who in this story do not fair as well, and who in the real world are only a minor percentage of the population.