Authorities say a wildfire burning in a rugged area of Nevada's vast former nuclear proving ground is 60 percent contained.
No radiation has been detected, and National Nuclear Security Administration spokeswoman Dona Merritt says aerial mapping Friday showed the fire has charred about 5 square miles. It's burning about 100 miles northwest of Las Vegas.
No injuries are reported, and officials say no structures, roads, power lines or other facilities are threatened in the sprawling former Nevada Test Site.
A separate 2-square-mile fire and another smaller fire have been contained.
About 100 firefighters are battling the fires, along with three air tankers, a spotter plane and a helicopter.
The blazes were sparked by lightning Monday in a remote restricted area north of the Nye County community of Amargosa Valley and east of Beatty.
THIS IS A BREAKING NEWS UPDATE. Check back soon for further information. AP's earlier story is below.
One lightning-sparked wildfire was contained and firefighters were battling a second blaze Friday in a remote undeveloped part of the vast federal nuclear testing reservation formerly known as the Nevada Test Site, a National Nuclear Security Administration official said.
About 100 firefighters with support from three air tankers, a spotter plane and a helicopter were fighting the blazes touched off Monday in rugged mountain and desert terrain about 100 miles northwest of Las Vegas.
The blazes covered more than 9 square miles, but no injuries were reported and officials said no structures, roads, power lines or other facilities in the sprawling federal nuclear proving ground were threatened.
Air monitors detected no release of radiation, said Dante Pistone, an NNSA spokesman in North Las Vegas.
"There have been no positive readings," Pistone told The Associated Press. "These fires are in remote locations and not near any historic testing areas."
The larger fire, dubbed the Timber fire, was burning pinyon, sage and cheatgrass well north of the Nye County community of Amargosa Valley and east of Beatty. Pistone said it was about 25 percent contained.
The separate Weston Fire, several miles southeast of the Timber fire, was 100 percent contained.
At a combined 6,000 acres, the two wildfires at the Nevada National Security Site were less than 5 percent the size of the Las Conchas fire that has been burning since June 26 in the mountains near NNSA facilities in Los Alamos, N.M. That fire was reported at 40 percent containment Friday.
Pistone said there was no firm estimate about when the Timber fire in Nevada would be contained. He said that with no infrastructure threatened some parts of the fire might eventually be allowed to burn out.
The renamed Nevada Test Site encompasses 1,375 square miles, nearly the size of Rhode Island. It is surrounded on three sides by the 4,562-square-mile Nellis Air Force Base bombing range. Combined, the restricted federal reservation is larger than the state of Connecticut.
The test site hosted 928 full-scale nuclear tests involving 1,021 nuclear detonations from 1951 to 1992, when the U.S. agreed to a moratorium on full-scale nuclear testing.
Most areas of the site where weapons tests were conducted have been decontaminated in recent years. Some areas have been converted for anti-terrorism training. Weapons-grade plutonium, highly enriched uranium and high explosives are handled at a $100 million bunker built for assembly and disassembly of nuclear weapons and experiments.