A helicopter helping battle a large Utah wildfire crashed Friday, with no immediate word on the conditions of the two people aboard, federal officials said.

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

Officials in Sevier and Millard counties did not immediately respond to questions about the crash, and the FAA and wildfire officials didn't have information on the conditions of the two people who were on board.

The U.S. Forest Service at Fishlake National Forest said in a post on social media that emergency personnel were on the scene.

"Our top priority is responding to the incident. Local, state, and federal authorities are assisting in the response," it said. "Information will be released as soon as it is available. Please be patient as the response to this incident continues to occur and safety actions are prioritized first."

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.

The NTSB said its preliminary information is that "the helicopter crashed in remote terrain under unknown circumstances during firefighting operations." The agency said its investigators are expected to arrive in Richfield by Saturday night.

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

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.

As of Friday, there are eight large active blazes burning across more than 331,000 acres in Utah, according to the state's wildfire dashboard.

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.