Idaho and Montana are worst hit

"We're hoping the situation is past its crisis stage," said fire information officer Jack Kendley, speaking from Montana.

Despite his optimism, the state's governor has ordered the closure of 7.2 million acres of public land in a desperate attempt to stop 19 major fires continuing to sweep through the state.

High cost

On Saturday, Head of the Federal Emergency Management Agency James Lee Witt toured some of the worst hit areas, and promised further federal funds to help authorities meet the cost of the fires.

Fighting the flames has so far cost an estimated $62m in Montana alone.

The cost of fighting Montana's fires has been huge

Eight firefighters have been killed battling this summer's blazes, which officials say are the worst for decades.

The latest victim died when the fire truck he and a colleague were using to fight a fire in Wyoming became engulfed by the blaze.

In addition, two people have died from heart attacks while fleeing their homes, and one reserve firefighter was killed in a training exercise.

Lightning strikes are constantly threatening to spark new blazes. Officials say they believe about 70 smaller fires have been started by lightning over the weekend.

Fire experts are seeking out the fire's key 'hot spots'

Despite reports that some of the fires have been started deliberately, investigators say they have identified only two that appear suspicious.

Authorities in Montana say they will allow student fire fighters to return to classes three weeks late if they remain fighting the blazes.

"These students are putting themselves at risk to protect our environment, and it is appropriate we assist them in their efforts," said State Higher Education Commissioner Richard Crofts.

Backfire mistake

However angry residents from Montana's Bitterroot valley have demanded an explanation after fire crews mistakenly destroyed a dozen homes.

Firecrews were trying to create a 'backfire' - an artificial and supposedly controlled blaze designed to create a gap to stop the main fire spreading.

"It was careless disregard for life...it was arson," said one resident, Joan Giles, who saw her home destroyed.

About 50 homes in the district have now been destroyed, where fires cover about 175,000 acres.