MEDFORD, Ore. — A lightning-caused wildfire in southern Oregon's Lake County has grown dramatically, prompting officials to urge some residents near a reservoir to leave their homes.

MEDFORD, Ore. — A lightning-caused wildfire in southern Oregon's Lake County has grown dramatically, prompting officials to urge some residents near a reservoir to leave their homes.

Fire officials estimated late Thursday that the Barry Point Fire has burned nearly 12 square miles, or 7,500 acres, and made a push during the day toward Drews Reservoir. Authorities advised residents on the reservoir's south shore that they should consider leaving.

A fire management spokesman did not immediately return an inquiry about how many people were in the area. Oregon Red Cross spokesman Thomas McCann said 15 families might be affected.

A Forest Service campground was closed earlier and residents of two homes in the Fremont-Winema National Forest were warned of potential danger.

The fire, which started Monday about 20 miles southwest of Lakeview, is about 25 percent contained.

A fire lookout tower considered to be in jeopardy got a protective wrapping, Forest Service spokeswoman Lisa Swinney said earlier Thursday.

Lightning last weekend set off dozens of fires in Oregon. Southwest of Medford, along the Oregon-California border, the Forest Service said crews made progress on a complex of small fires centered on the Red Buttes Wilderness area. An air inversion minimized fire growth, spokesman Paul Galloway said.

The largest of those fires is estimated at 230 acres and was 5 percent contained.

To the east, a large fire from Nevada crept north into Harney and Malheur counties.

Along the Idaho border in the far eastern part of the state, firefighters said they had established containment lines around an 8-square-mile fire south of Vale.

In central Oregon, a 2-square-mile fire near Sisters that briefly threatened a subdivision earlier in the week was close to full containment.