Three firefighters have been killed as a "hellstorm" of flames apparently enveloped their vehicle when it crashed while they were battling a blaze in Washington state.
Four other firefighters were hurt, including one critically, on Wednesday, as crews fought raging wildfires advancing on towns in the north-central part of the state, some of the many blazes burning uncontrolled throughout the West.
Drought and heat have combined to make this fire season one of the most active in recent years.
Nearly 29,000 firefighters are battling some 100 large blazes in states including Idaho, Oregon, Montana, Washington and California.
This season, 13 people have died battling wildfires, including the three in Washington, the National Interagency Fire Center in Boise, Idaho, said.
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The latest deaths happened in the scenic Methow River valley, northeast of Seattle, but few details were released as officials notified family members.
"The firefighters were engaged in initial attack operations and were involved in a vehicle accident when it is believed that the fire overtook the vehicle," a statement from Okanogan-Wenatchee National Forest said, relaying information from Okanogan County Sheriff Frank Rogers.
It wasn't immediately clear if the four injured also were involved in the crash.
"It was a hellstorm up here," Rogers told Spokane news station KXLY-TV.
"The fire was racing and the winds were blowing in every direction and then it would shift ... It was tough on 'em up here."
The National Weather Service has warned about weather conditions that could fuel fires in eastern Washington through to Friday.
Temperatures were expected to climb above 32C and relative humidity may drop as low as 14 per cent.
