A PG&E outage that knocked power out for thousands of San Francisco residents for most of Sunday was caused by the fog, an employee for the energy company told a broadcast news station.

According to NBC Bay Area, nearly 5000 Richmond district residents lost power at around 9:30 a.m. Sunday, after "an equipment failure in the area of California Street and 16th Avenue."

ABC 7 reports that the San Francisco Fire Department was first called to the epicenter of the outage "and closed all but one lane in both directions near the intersection" as they sprayed down some equipment on an area power pole.

PG&E spokesperson Mayra Tostado told the Ex that a "cross arm broke off,” causing the hours-long outage that snarled travel on Muni's 1 California line and "knocked out traffic signals in the area of California Street and Geary Boulevard between 17th and 18th avenues."

“We’re investigating exactly how that happened,” Tostado told the Ex Sunday. “That’s something that we could possibly find out today.”

But according to an unnamed worker who spoke with CBS 5 (aka KPIX), it's the weather formation known by some as "Karl" that's to blame.

"A PG&E worker at the scene told KPIX that condensation from fog, possibly mixed with dirt and grime, likely caused an electrical arc," the news station reports.

As three things you're extremely likely to find in San Francisco skies are dirt, grime, and fog, perhaps it's a miracle we have any power on at all! At any rate, Tostado tells the Ex that “We were able to restore service to more than 3,000 customers within a half hour." The remaining customers, NBC reports, remained in the dark until "late Sunday night," when one can only assume that the fog was banished from that area and others forevermore.

Related: Ask A San Francisco Native: Has The Fog Always Been Named Karl?