PG&E stocks were hammered today as investigators work to determine if the utility was responsible for the fires in Northern California. PG&E has issued a statement saying it wasn't going to speculate about the cause of any of the blazes but also saying that hurricane-strength winds did blow trees and other debris into power lines. KCBS, KPIX-5, and Chronicle Insider Phil Matier explains the effect of past PG&E accidents and what it means for the Northern California fires.