RICHFIELD, Utah (AP) — A heavy-lift helicopter with two people on board battling a large Utah wildfire crashed while, in a separate fire in Oregon, firefighters worked to corral an uncontained blaze that killed a bulldozer operator, officials said Friday.

There was no word on the condition of the people aboard the helicopter as officials said they couldn't immediately reach the crash site.

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'Unexpected and rapid growth' kills in Oregon

During firefighting operations in Oregon, 47-year-old Jason Ensign died Thursday while operating a dozer for a timber company. The Wrights Spring fire escalated with “unexpected and rapid growth” and cut off Ensign's escape route, the local sheriff's department said.

The fire started on Wednesday in south-central Oregon east of the town of Chiloquin. It had burned almost 14 square miles by Friday with no containment, according to the U.S. Forest Service. Extremely hot and dry weather has caused erratic fire behavior, officials said.

Helicopter crashes in Utah

The downed helicopter was one of seven working a fire in central Utah that was caused by lightning on July 27. It crashed near Richfield, which is about 160 miles south of Salt Lake City, the Federal Aviation Administration said.

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Conditions were good enough for aircraft to fly when the helicopter crashed, said Tyler Hecht with the Great Basin Incident Management Team.

The Sikorsky S-64 helicopter had been working in an area with steep terrain. It ignited another fire when it crashed. Hecht said at an afternoon press conference he did not know how long the helicopter was flying before it crashed.

Response teams had not been able to get to the scene of the accident by Friday evening because of the flames, but hoped to get there in the next 24 hours, officials said.

“We didn't want to put them at bigger risk,” Sevier County Sheriff Nathan Curtis said. “We'll get them in there as soon as we can."

It was unknown if fire had overrun the crash scene, Hecht said.

Firefighting efforts were paused after the accident but later resumed, they said.

The National Transportation Safety Board and FAA will investigate, but they may not be able to safely reach the scene immediately if the wildfire is burning nearby.

Sikorsky S-64 “Skycrane” helicopters are used commercially and by government agencies for firefighting and other purposes. They can be equipped with tanks to drop water or fire retardant onto blazes.

Fire crews were warned Friday morning that there would be erratic winds, dry fuels and hot temperatures as well as the potential for dry thunderstorms and lightning. Red flag warnings were in effect.

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The fire on the Fishlake National Forest near the small community of Kanosh, Utah, had grown to 165 square miles and was 19% contained by Friday morning. More than 600 firefighting personnel are battling the blaze, which has triggered evacuations and destroyed at least six structures as it burns through timber, brush and grass.

Months of dry weather, a record lack of snow in some areas, hot spells and erratic winds have contributed to blazes in Utah and other parts of the West.

Four firefighters were killed, and a fifth was injured after they were overcome by a fast-moving wildfire in Colorado in June. The firefighters tried to shield themselves by deploying tentlike emergency shelters as flames overran their position.