SAN FRANCISCO (AP) — Lightning has sparked nine wildfires in the northeastern corner of California, and a stubborn blaze to the west in Mendocino County continues to challenge crews.

Fire officials say the new fires in Lassen, Modoc and Shasta counties are not threatening any structures, but crews are trying to contain them so they can focus on the large wildfires.

A wildfire sparked by lightning July 30 has burned 13 ½ square miles of dry brush and timber in Mendocino County.

Copyright 2014 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.