San Diego was reportedly dragged into the big blackout by surrounding areas.
A transmission executive says it wasn't until transformers in the Coachella Valley shut down and a Mexican power plant lost power that the problem spread throughout the county, according to our media partner, the North County Times.
An Arizona utility worker initially triggered the power outage on Sept. 8, causing millions of people to lose power. It left parts of Arizona, Baja California, and Imperial County with only San Diego County as a source of power.
That was too much for San Diego's system, so it disconnected, causing the large-scale power outage.
Read the full story at North County Times.