Dozens of wildfires burning across the drought-parched U.S. Northwest on Tuesday have destroyed scores of structures, sparked evacuation orders for thousands of people, and killed at least 27 wild horses.

More than 100 homes have been destroyed since Friday in Washington state, Idaho and Oregon, authorities said.

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About 200 U.S. soldiers have been called in to reinforce civilian firefighters battling almost 90 blazes that have blackened more than 1 million acres (400,000 hectares) across the country's arid West. The mobilization was the first of its kind since 2006.

To help battle the blazes, the U.S. Forest Service said fire managers are considering asking Australia and New Zealand to lend firefighters. Canadian crews, smokejumpers, and air tankers have already been assigned to northern Idaho and Montana.

The year-to-date acreage burned so far is about 7.1 million acres (2.9 million hectares) nationwide, according to the National Interagency Fire Center in Boise, Idaho. It is the first time in 20 years that the area charred has exceeded 7 million acres by this date, the center said.

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In north-central Washington, a cluster of wildfires destroyed at least 35 homes and 21 outbuildings on the outskirts of Chelan, a resort town at the southern tip of Lake Chelan, sheriff's spokesman Rich Magnussen said.

Officials halved to 1,000 the number of residences under evacuation orders on Tuesday from Monday as previously burned areas cooled, while firefighters prepared to face strong winds forecast over coming days, Magnussen said.

Officials expected to find as many as 50 homes and many more outbuildings burned as the county assessor continues in-person tallies, Magnussen said.

In Idaho, at least 27 wild horses were burned to death by a massive wildfire southwest of Boise, said U.S. Bureau of Land Management spokeswoman Heather Tiel-Nelson.

Two other wild horses were euthanized, and Tiel-Nelson said more may be found killed by the so-called Soda fire, which was nearing containment on Tuesday after burning more than 280,000 acres (110,000 hectares).

In west-central Idaho, dozens of residents had to evacuate their homes near the resort town of McCall. Others were told to prepare to leave at a moment's notice.

In northern Idaho, firefighters battling a 58,000-acre (23,000-hectare) blaze reported cooler temperatures and higher humidity, which let them make significant gains for the first time since it was sparked by lightning on Thursday.

The so-called Clearwater Complex of fires, which was at about 25 percent containment on Tuesday, has destroyed 50 houses and 80 outbuildings near the town of Kamiah, Idaho. An elderly woman died when she fell and hit her head as she was trying to secure her backyard chickens and flee with her husband.

In central Oregon, 26 dwellings were destroyed over the weekend. About a dozen large fires are burning across the state, threatening hundreds of structures, authorities said.

(Reporting by David Ryder in Chelan, Washington, Laura Zuckerman in Salmon, Idaho, and Courtney Sherwood in Portland, Oregon; Writing by Eric M. Johnson; Editing by Mohammad Zargham and Eric Walsh)