LAS VEGAS, July 10 (UPI) -- One of two wildfires burning in Nevada is now considered the largest the state has ever seen, burning more than 25,000 acres, officials said.

The Bison Fire in Carson Valley is 40 percent contained as more than 1,000 firefighters battle the blaze sparked by lightning Thursday, the Reno (Nev.) Gazette-Journal reported Tuesday.


Fire officials project the fire should be fully contained Monday.

"Additional heavy helicopters assisted in the aerial firefighting efforts today, with winds posing less of a problem on certain areas of the fire than in past days," Sierra Front fire responders said in a statement.

A few structures that were part of the early 20th century Slater mine were burned on property owned by the U.S. Bureau of Land Management but no other structures were reported to be in danger due to the Bison fire.

Meanwhile, the Carpenter 1 fire has consumed nearly 20,000 acres on Mount Charleston, officials said.

That fire also was started by a lightning strike on the western side of the mountain July 1.

The blaze is 10 percent contained and firefighters expect full containment by July 19.

More than 500 residents have been evacuated from Kyle, Lee and Trout canyons due to the blaze, KVVU-TV, Las Vegas, reported Wednesday. At least one person -- a Pahrump camp worker -- suffered heat exhaustion from the fire.

The Carpenter 1 blaze claimed its first structure Tuesday, a commercial building near Prospect Ranch, though officials said no residences are currently threatened.