'Extreme And Aggressive' California Wildfires Force Thousands To Evacuate

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A wildfire in the foothills near Yosemite National Park has consumed eight structures — and is threatening 1,500 more in tiny Mariposa, Calif.

The town's 2,000 residents have been ordered to evacuate because of the blaze known as the Detwiler Fire, and Gov. Jerry Brown has issued a state of emergency for Mariposa County.

The California Department of Forestry and Fire Protection, known as Cal Fire, posted on its website that "firefighters experienced extreme and aggressive fire behavior" on Tuesday. "Firefighters on the ground as well as aircraft are actively working to contain and suppress the fire."

The Detwiler Fire has burned more than 45,000 acres and is just 7 percent contained, and it threatens "culturally and historically sensitive areas," the agency says.

"I haven't seen these conditions in a long time, it's a wind driven, slope-driven, fuel-driven fire," Cal Fire's Jerry Fernandez told Fresno's ABC affiliate.

Mariposa is about 150 miles east of San Jose, Calif.

About 4,000 people have had to flee their homes because of the fire, The Los Angeles Times reports; temperatures are expected to drop a few degrees on Wednesday, but humidity and winds will likely continue.

Cal Fire spokesman Koby Johns says that the cause of the fire is unknown but that its speed is due to the region's drought being followed by heavy rains.

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"Lots of tall grasses, lots of bushes, and they essentially provide like a ladder to the trees," Johns told Valley Public Radio's Ezra David Romero. "A lot of those trees are dead oak trees and then you have fire spreading from tree to tree."

Drone grounds helicopter fighting another California fire

In the city of Saratoga, Calif., near San Jose, the pilot of a water-dropping helicopter was forced to ground the aircraft when a drone appeared unexpectedly, Ryan Cronin of the Santa Clara County Fire Department told the Times.

"It really put them in a precarious position," he said of the drone. "We didn't appreciate that much."

Wildfires have been especially prevalent this year. Fires have burned 4.4 million acres so far in 2017, compared with 2.7 million acres over the same period in 2016, according to the National Interagency Fire Center. Large fires are currently reported in 12 states, all in the western U.S.