An underground vault fire and/or an explosion caused a power outage Sunday evening starting at around 6:30 p.m. which affected 1,400 PG&E customers in SOMA and shut the lights on the Bay Bridge. ABC7 also lost power in their studio momentarily during their 6 p.m. broadcast. The lights on the bridge remained off most of the evening, but there was no reported interruption in traffic flow. The explosion/fire took place at 2nd and Harrison, and the cause isn't known. Looks like it's underground explosion season again!