FRESNO, Calif. (AP) -- A giant wildfire raging out of control spread into Yosemite National Park on Friday as authorities urged more evacuations in nearby communities where thousands have fled during the week as flames marched through the timbered slopes of the western Sierra Nevada.
The fire closed backcountry hiking in the park, but was not threatening the popular Yosemite Valley region.
The fire grew from 99 square miles to more than 165 square miles overnight and was only 2 percent contained. Smoke blowing across the Sierra into Nevada forced officials in several counties to cancel outdoor school activities and issue health advisories, especially for people with respiratory problems.
"Most of the fire activity is pushing to the east right into Yosemite," said Daniel Berlant, spokesman for the California Department of Forestry and Fire Protection.
The fire was threatening about 4,500 residences, according to the U.S. Forest Service. Officials issued voluntary evacuation advisories for two new towns on Friday - Tuolumne City, population 1,800, and Ponderosa Hills, a community of several hundred - which are about five miles from the fire, spokesman Jerry Snyder said.
A mandatory evacuation order remained in effect for part of Pine Mountain Lake, a summer gated community that's a few miles from the fire line.
Already, the blaze has destroyed four homes and 12 outbuildings in several different areas, Snyder said. One firefighter also sustained a heat-related injury.
While the park remained open, the blaze closed a 4-mile stretch of State Route 120, one of three entrances into Yosemite on the west side. The other western routes and an eastern route were open.
Within the park, the blaze was burning on about 17 square miles in a remote area around Lake Eleanor, about 4 miles northwest of Hetch Hetchy reservoir, Yosemite spokeswoman Kari Cobb said.
Backcountry permits are required to hike in that area, Cobb said, and the park was no longer issuing those and had contacted every person who had received a permit to go there. Two roads into that area were closed and occupants of a campground near the Route 120 west entrance were relocated.
"We don't have anybody we know of in that area based on the permits we have out now," she said.
The fire was more than 20 miles from Yosemite Valley and skies there were "crystal clear," Cobb said.
The spectacular valley carved by glaciers offers visitors such iconic sights as the Half Dome and El Capitan rock formations and Bridalveil and Yosemite falls.
"Right now there are no closures and no visitor services are being affected in the park," Cobb said. "We just have to take one day at a time depending on fire activity."
Officials also have advised voluntary evacuations of more than a thousand other homes, several organized camps and at least two campgrounds in the area outside the park's boundary. More homes, businesses and hotels are threatened in nearby Groveland, a community of 600 about 5 miles from the fire and 25 miles from the entrance of Yosemite.
"Usually during summer, it's swamped with tourists, you can't find parking downtown," said Christina Wilkinson, who runs Groveland's social media page and lives in Pine Mountain Lake. "Now, the streets are empty. All we see is firefighters, emergency personnel and fire trucks."
Many area businesses have closed and people who had vacation rental homes have cancelled plans, local business owners said.
"This fire, it's killing our financial picture," said Corinna Loh, whose family owns the still-open historic Iron Door Saloon and Grill in Groveland. "This is our high season and it has gone to nothing, we're really hurting."
Loh said most of her employees have left town. And the family's Spinning Wheel Ranch, where they rent cabins to tourists, has also been evacuated because it's directly in the line of fire. Two outbuildings have burned at the ranch, Loh said, and she still has no word whether the house and cabins survived.
"We're all just standing on eggshells, waiting," Loh said.
The governor's emergency declaration finding "conditions of extreme peril to the safety of persons and property" frees up funds and firefighting resources and helps Tuolumne County in seeking federal disaster relief. More than 2,000 firefighters are already battling the blaze.
The Yosemite County Tourism Bureau based in Mariposa has been helping tourists displaced by the fire to find new accommodations in other park-area towns, said director Terry Selk.