Published: Aug 25, 2013 9:49 AM EDT

GROVELAND, Calif. (AP) - The weather could be a negative factor today in efforts to gain ground on a Chicago-sized wildfire that's burned its way into Yosemite National park.
    
Firefighters say they're bracing for strong winds of up to 30-40 mph that could push the raging fire further into the northwest edge of the park, threatening thousands of rural homes. More than 5,500 homes are already threatened and at least four have been destroyed.
    
The massive, 203-square-mile blaze is also burning in the vicinity of two groves of giant sequoias that are unique the region, prompting park employees to take extra precautions of clearing brush and setting sprinklers.
    
The towering trees are among the largest and oldest living things on earth.
    
The Rim Fire is only about 7 percent contained.

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