WILLIAMS, Calif. (AP) — State fire officials are planning to bring in more resources to battle a pair of wildfires in Northern California that doubled in size overnight and is threatening nearly two dozen residences.

The fires in Colusa County — referred to as the Sixteen Complex — had grown to more than 11 square miles as of Thursday morning. They were fueled by strong winds from a thunderstorm system that also pummeled the region with lightning strikes.

State fire spokesman Daniel Berlant says Wednesday’s lightning sparked dozens of fires in the eastern Sacramento foothills, with Amador, El Dorado and Calaveras counties hit particularly hard.

Those fires burned a small number of acres before they were contained.

Containing the Sixteen Complex in Colusa County, however, has proven harder. The fire is 10 percent contained and has resulted in an evacuation advisory for the Cortina Rancheria area.

Copyright 2012 The Associated Press.