BOISE, Idaho (AP) — For wildland firefighter Anne Veseth, the danger came not from out-of-control flames, but from above: She was struck by a falling tree on Sunday, ending her life at just 20 years.

Exactly what happened is now the subject of a federal investigation.

When Veseth died, she and other members of her 20-person crew were trying to extinguish the 43-acre Steep Corner fire near Orofino. They were establishing and reinforcing a fire line on one perimeter of the blaze, U.S. Forest Service spokesman Phil Sammon said.

"It's a harsh reminder that this is dangerous stuff, and the qualification and safety and training we commit to is paramount," said Sammon, who is based in Missoula, Mont.

At least two federal investigators from the U.S. Department of Labor's Occupational Safety and Health Administration were on the scene in Orofino, looking into Sunday's accident.

An investigation could take up to six months, said Deanne Amaden, a Labor Department spokeswoman in San Francisco. Typical investigations focus on the activities leading to the accident, including whether federal rules were being followed and whether appropriate plans were in place, she said.

In 2003, for instance, an investigation into two firefighter deaths in Idaho concluded that poor judgment and numerous violations of safety standards contributed to the fatalities of Shane Heath, 22, of Melba, and Jeff Allen, 24, of Salmon.

In the wake of the deadly Cramer Fire, at least six Forest Service employees were disciplined. Heath and Allen had radioed for a helicopter at least twice when the fire advanced their direction, but when one was finally sent, the area was too smoky to find the men.

Between 2002 and 2011, only two of 58 U.S. Forest Service wildland firefighter fatalities came from hazardous trees like the one that killed Veseth.

The most dangerous line of firefighting work, according to the agency's statistics, involves helicopters, where accidents killed 22 firefighters during the period.

Eight people died in large air tanker incidents, 10 were killed when they were overtaken by flames, 11 were killed in driving accidents while three deaths came in falls from vehicles or structures. Two fatalities came after heart attacks.

As of July 31, 2012, eight firefighters have died this year in wildland fire incidents, according to the Federal Emergency Management Agency.

Veseth's life will be remembered at a memorial service Saturday in Moscow, Idaho, her hometown. Family members Tuesday moved the venue from the local Catholic church to the larger Nazarene Church, given the expected crush of friends.

Veseth was a Type 2 firefighter, one of the agency's thousands of seasonal employees dispatched to the nation's forests during the spring and summer fire seasons.

The Forest Service said Veseth, a student at Lewis-Clark State College, in Lewiston, whose older brother also is a wildland firefighter in Idaho, had completed the safety courses required of every person in her crew.

Safety is the top priority in firefighter training, said Jill McCurdy, chief of fire and aviation training for the U.S. Forest Service. "It's the No. 1 key to all our training, not only personal safety but safety for the environment and all the people they're working with," she said.

In May, for instance, Veseth took a daylong fire line safety refresher course before she was deployed to fight blazes in Arizona and Colorado earlier this year.

That's after getting her first training in 2011, Veseth's initial year of wildland firefighting. That training included about a week of learning about wildfire behavior, human reactions on the fire line, and basic firefighting skills. Training includes the art of wielding a Pulaski, a tool that's part-shovel, part-axe and is used to establish fire breaks intended to stop approaching flames.

"There's a hands-on demonstration that they can use of all the equipment, hand tools, backpack, their fire shelter, deploying it, using drip torches, pumps, working with other units on a fire line," Sammon said, of the training Veseth received. "It's arduous and demanding work."

Once on the line, Type 2 crews carry backpacks weighing 45 pounds or more, often hike several miles, and sometimes spend 12 hours or more digging line.

Crews like Veseth's should be able to dig more than 250 feet of fire line in an hour, according to Forest Service standards.

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