A Northern California wildfire sparked by lightning has burned 100 square miles of dry brush and timber in the Klamath National Forest near Happy Camp.

The U.S. Forest Service says crews are working to keep flames away from homes in the communities of Seaid Valley and Hamburg. No structures have burned.

The fire that began Aug. 11 was 15 percent contained late Sunday. Officials say while the blaze was very active on Sunday there was no significant growth.

The fire is burning along Highway 96, which remained open with traffic control measures in place.

Happy Camp is just south of the Oregon border.

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