(SACBEE) - Fueled by hot winds and unrelenting heat, Northern California fire crews battled into the night Saturday on an explosive wildfire in western Yolo County while struggling to control the 13,000-plus acre Pawnee Fire in Lake County, which had broken its containment during the afternoon.

The County Fire near Guinda, 10 miles north of the Cache Creek Casino and Resort, had quickly grown to 8,000 acres with no containment as of 9 p.m., according to Cal Fire spokesman Scott McLean. Two hours earlier, the fire had encompassed 4,000 acres, and it had been 1,000 acres around 5 p.m. before jumping a road.

Cal Fire couldn't determine if any structures had been destroyed or damaged, but 30 structures were threatened as of 9 p.m., McLean said.