MEDFORD, Ore. (CBS SF) — Firefighters battling the Klamathon Fire along the California-Oregon border Friday discovered a body within a residence during a welfare check of an evacuated area, authorities said.

The blaze ignited Thursday afternoon and quickly grew, forcing the evacuation of the small border town of Hornbrook. By 7:21 a.m. Friday, the Klamathon Fire had grown to 8,000 acres and was just 5 percent contained.

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Cal Fire spokeswoman Cheryl Buliavac said numerous homes had been damaged or destroyed as the fire raced through Hornbrook.

“We are still in the early stages of aggressively attacking this fire with both ground and air resources,” she said.

The southbound lanes of I-5 that had been closed overnight were reopened at 6:30 a.m., but the local off-ramps remained closed in the area of the fire.

Buliavac said the fire was spreading to the northeast and northwest of Hornbrook in the rugged, rural region.

“Yesterday, the Red Flag conditions generated very, very erratic winds that pushed this fire all over,” she said. “Again, we are anticipating those winds today.”

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Buliavac said the winds present a challenge to firefighters because they “can shift very quickly, so it’s very dangerous.”

A DC-10 air tanker arrived early Friday to join in the aerial attack of the fire. On the ground, Cal Fire was joined by agencies from the surrounding communities and Oregon.

California officials say they are temporarily crossing a hatchery and two other public areas because of their proximity to a deadly blaze near the Oregon state line.

The California Department of Fish and Wildlife says the Iron Gate Fish Hatchery along the Klamath River, the Klamathon Road fishing access below the hatchery and the Horseshoe Ranch Wildlife Area have been closed as a precaution.

California Gov. Jerry Brown has declared a state of emergency for Siskyou County, citing “extreme peril” to people and property. Hornbrook is located in Siskyou County.

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An evacuation shelter has been opened at the Jackson Street School while a large animal shelter has been established at Siskiyou Fairgrounds.