SALT LAKE CITY — Favorable weather conditions allowed progress to be made Sunday as crews continued to battle wildfires in several areas of the state.

Firefighters have contained a 10-square-mile wildfire on the Utah-Nevada border where an air tanker crashed last week, killing two crew members.

The lightning-caused White Rock Fire, burning about 150 miles northeast of Las Vegas in eastern Nevada and western Utah, was 100 percent contained Friday night after a weeklong battle, officials said. Most of the fire was in Nevada.

A Lockheed P2V air tanker was dropping retardant on the fire when it crashed June 3 into a mountain slope a quarter-mile inside the Utah border, killing pilots Todd Tompkins and Ronnie Chambless, both of Boise, Idaho.

Federal investigators have recovered a cockpit voice recorder from the air tanker that may provide clues into the cause of the crash.

Efforts to battle fires were aided Sunday by cooler temperatures, higher humidity and reduced wind speeds.

In southern Utah, the Lost Lakes Fire has burned nearly 2,100 acres southwest of Teasdale in Wayne County since June 3, according to the U.S. Forest Service and the Great Basin National Incident Management Team.

More than 550 firefighters were battling the blaze Sunday, with 16 engines and seven helicopters. As of Sunday morning, the fire was 50 percent contained.

Strong winds have made the fire tricky to battle, officials said. Helicopters dropped crews near hotspots Saturday until winds grounded air operations.

Meanwhile, the 2,018-acre Box Creek Fire near Greenwich was 40 percent contained. Some residents have been evacuated, but no property has been damaged thus far. Fire officials were hopeful that the homes would be spared.

"The weather today is firefighter heaven. Somebody above is taking care of us today," public affairs officer Richard Helmerick told The Associated Press on Sunday. "Yesterday we had terrible wind conditions. But we're expecting two to three days of good weather. We're optimistic."

In Box Elder County, the Copper Mountain Fire has burned about 1,200 acres on the east side of the Pilot Mountains near U.S. 30 on the Utah/Nevada border, according to the Bureau of Land Management.

As of Sunday evening, the fire was 60 percent contained. The fire had been burning since Saturday. The cause remains under investigation, but officials estimate the blaze could be under control by Monday.

The Box Creek Fire began in mid-May as a prescribed burn in Fishlake National Forest by the U.S. Forest Service, but high winds caused it to grow last week. The Lost Lake Fire is believed to have been human-caused.

Contributing: The Associated Press