Efforts to tame a raging wildfire that has destroyed some 200 homes near Lake Tahoe suffered a setback when a backfire set by firefighters to control the blaze jumped a fireline, forcing a new round of evacuations, authorities said.

Firefighters were working to protect a development outside South Lake Tahoe when the blaze expanded, prompting the evacuation of a 300-home subdivision. About 2,000 people evacuated, according to South Lake Tahoe Police Lt. Martin Hale.

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"It's a fairly populated area," said U.S. Forest Service spokesman Tim Evans. "That certainly is not good news for our firefighting efforts here."

• PHOTO ESSAY: Lake Tahoe Wildfire Jumps Fireline

The fire started Sunday near the south end of Lake Tahoe. By Tuesday evening, it had consumed more than 3,000 acres — about 4.69 square miles — and was about 44 percent contained, fire officials said.

Officials said the blaze jumped the fireline because firefighters set a backfire as part of their efforts to keep the main blaze from reaching more houses. When the wind picked up, embers crossed the fireline. Previously, firefighters had been able to contain the small spot fires that erupted.

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The blaze moved so quickly that two firefighters were forced to deploy the emergency shelters firefighters carry to protect themselves during burnovers as a last resort, said Chuck Dickson, a U.S. Forest Service spokesman. They managed to walk away uninjured, he said.

The danger to homes had diminished overnight as firefighters got a badly needed advantage on the inferno. But it was still burning throughout the day along rugged, uninhabited slopes and authorities had cautioned that strong winds forecast to arrive Wednesday could fan the flames.

Earlier in the day, other families whose homes were in the path of the wildfire returned to their property, finding some houses reduced to charred ruins and others largely unscathed, except for the odor of smoke and a blanket of ash.

Investigators determined that the fire began near Seneca Pond, an area popular with runners and teenagers in this resort area along the California-Nevada state line. They also said they were close to identifying its cause. An announcement on that was expected later Tuesday.

Authorities have said they believe the fire was caused by some kind of human activity, but U.S Forest Service officials said there was no indication it was intentionally set.

The forest here was so dry that a discarded cigarette butt or match could easily have ignited the fire, Forest Service spokeswoman Beth Brady said. The area was also dotted with the remnants of illegal campfires, she said.

Experts have said California and the rest of the West are entering what could be a long and dangerous fire season after one of the region's driest winters on record. They warn that years of logging, development and forest mismanagement have left the Tahoe area particularly vulnerable to catastrophic wildfires.

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