Firefighters combating a group of lightning-caused fires have been frustrated by steep, virtually inaccessible terrain near Panther Ridge in the Rogue River-Siskiyou National Forest.

Rugged conditions have limited fire crews' access to the fast-growing Blossom Fire, with hand crews continuing line construction along the northern portion of the fire.

The fire, which made a run to the top of Panther ridge, grew from 166 to 492 acres Thursday, said public information officer Tom Lavignino of the U.S. Forest Service.

"That's the one causing us the most concern - I couldn't ask for a worse place to place a fire," said Lavignino, speaking Thursday from the Agness Incident Base Camp.

Centered about halfway between the Rogue River and Panther Ridge, the Blossom Fire is the largest of three fires caused by lightning strikes during a July 21 storm.

"It's extremely rough, unsafe and inaccessible - without boots on the ground, you're not going to get a handle on it," continued Lavignino. "It's going to be a long battle."

Lavignino said helicopters have flown over the fire to find hot spots where efforts need to be placed, and are dumping water dipped out of the Rogue River on them.

Three 20-person hand crews, three engines and one water tender are continuing line construction along Panther Ridge above the northwest portion of the Blossom Fire. Air tankers also are continuing to assist firefighters. Two additional heavy-lift helicopters have been ordered to join forces with the other three heavy-lift helicopters. In total, the blazes have charged more than 600 acres.

On Thursday, fire crews continued line construction, holding existing fire breaks around Solitude Fire using six 20-person hand crews. That fire grew slightly from 103 to 123 acres Thursday as hand crews aggressively worked to contain the flames south of Brushy Bar, along the Wild and Scenic section of the Rogue.

The eight-acre Huggins Fire has been contained and is being monitored by hand crews who mopped up burning material Friday.

No river, road or trail closures were expected Friday, but increased traffic is expected on Forest Road 33. The Eden Valley Campground has been closed so firefighters can use it, but other campgrounds remain open.

No injuries from the fire have been reported, but on Thursday but a heart attack victim was taken to Curry General Hospital in Gold Beach by paramedics assigned to fire. CalOre Life Flight EMTs happened to be nearby when the man, a truck driver from Manitoba, Canada, became ill while looking for a shortcut from Gold Beach to Grants Pass.