Officials say a 100-acre brush fire that has damaged three homes in a rural community in north San Diego County was sparked by human activity.

California Department of Forestry and Fire Protection Capt. Nick Schuler says the fire is 15 percent contained Sunday evening and is expected to be fully surrounded early Monday.

No structures are threatened and no injuries have been reported.

Schuler says it's unclear whether the blaze was intentionally set or an accident.

The fire broke out just before 3 p.m. Sunday in a rural area 10 miles east of Fallbrook.

Schuler says investigators are assessing the damage to the three homes.