The power was jolting on and off in Episode 2, and while nothing major came of it, that seems like a definite sign L.A. will be plunged into darkness soon. The wise, young Tobias already predicted doom for the electricity as there soon won't be enough people to man the power stations, taking down internet, phones and everything else 21st century USA holds dear. As soon as the lights go out for good, fear will flow through the city and again, the panic will escalate. That's the definite theme throughout the first couple of episodes, the escalation of the problem from being a minor 'flu' to a widespread catastrophe, and going dark is the next stage in the process.