Feb. 20 (UPI) -- A fire at a utility substation in Oakland, Calif., caused a major power outage Sunday that left more than 50,000 residents in the dark before electricity was restored to most affected households overnight.
Approximately 45,000 of the initial 54,000 households that lost power from the Bay coast to the Oakland hills were back online by 9 p.m. but Tamar Sarkissian, a spokesperson for Pacific Gas & Electric, said Sunday night that at least 8,500 residents had to wait until the predawn hours Monday or much later for the lights to come back on.
The power outage began shortly before 1 p.m. and also shut down the Oakland International Airport, where throngs of passengers were forced to wait in crowded security lines for nearly two hours before flights and normal activity resumed.
Shortly before 1 p.m., the Oakland Fire Department responded to a report of a fire at the PG&E utility yard at the intersection of 50th Avenue and Coliseum Way. There, a transformer had burst into flames, sending brown smoke billowing into the sky, officials said.
It was unclear what caused the transformer to catch fire, and authorities did not immediately speculate whether the substation had been targeted amid a recent spate of power grid attacks across the country.
"Right now, PG&E says they have to wait to really look at all the equipment and determine what the cause of the fire is," a fire department spokesperson said.
Fire crews managed to extinguish the blaze by 4 p.m., but by that time the small fire had created a bigger emergency that also hampered public transportation for a short time throughout the region. Two draw bridges along Fruitvale Avenue and High Street were also frozen upright, marooning Alameda island residents for hours.
PG&E initially estimated the power would be restored by 3:30 p.m., but later revised its timeline to 6:30 p.m.
Power began flickering back in some areas around 5 p.m., and from there occurred intermittently throughout the night.