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Wildfires continue to burn in Western states

George Frey / Reuters

A house is surrounded by a burnt landscape, as a helicopter flies above after dropping water on the Quail Fire in Alpine, Utah, July 3, 2012. The fire started on Tuesday afternoon and spread quickly through the eastern end of Alpine and then up the mountain side. It is still out of control.

George Frey / Reuters

A plane drops slurry on the Quail Fire in Alpine, Utah, July 3, 2012.

George Frey / Reuters

Trees go up in flames above homes at the Quail Fire in Alpine, Utah, July 3, 2012.

Andy Carpenean / AP

A sudden wind shift draws smoke back over the top of Sheep Mountain as the Squirrel Creek fire spreads Tuesday, July 3, 2012 near Woods Landing, Wyo.

msnbc.com reports: As firefighters continue fighting the devastating Waldo Canyon blaze in Colorado, FBI agents are investigating what could have triggered the blaze, which forced more than 30,000 people from their homes.

Elsewhere in the state, lightning was to blame. But more typically, humans start wildfires. In 2011, humans started six times more fires than did lightning, scorching 5.36 million acres, according to government statistics.

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The worst fire season in recent history is taking its toll with large fires burning thousands of acres in Colorado while others consume areas in Montana, Utah, New Mexico and Wyoming.