As many as 9 million Californians could lose power Sunday in the biggest rolling blackouts in state history. The state’s grid operator said it expects to impose rotating outages this evening as record-breaking heat pushes the electric grid to the brink. Uncontrolled wildfires have already cut electricity to almost 70,000 customers in Southern California, downing power plants and transmission lines. The California Independent System Operator, which runs most of the state’s grid, declared a Level 2 emergency — the last step before ordering power cuts — after a power plant and a transmission line carrying power from Oregon to California went down unexpectedly.