After burning for nearly a week on the edges of California's Yosemite National Park, a massive wildfire of nearly 200 square miles has now crossed into it, and firefighters have barely begun to contain it. 
 
 In this undated photo provided by the U.S. Forest Service, the Rim Fire burns near Yosemite National Park, Calif. The wildfire outside Yosemite National Park — one of more than 50 major brush blazes burning... (Associated Press) 
 
 In this undated photo provided by the U.S. Forest Service, the Rim Fire burns near Groveland Ranger Station in Groveland, Calif. The wildfire outside Yosemite National Park — one of more than 50 major... (Associated Press) 
 
 In this undated photo provided by the U.S. Forest Service, the Rim Fire burns near Groveland Ranger Station in Groveland, Calif. The wildfire outside Yosemite National Park — one of more than 50 major... (Associated Press) 
 
 Hazy smoke from a wildfire more than 150 miles away near Yosemite National Park descended Thursday, Aug. 22, 2013, on Reno and the downtown casino district. Washoe County Health District officials issued... (Associated Press) 
 
 The Yosemite Valley, the part of the park frequented by tourists and known around the world for such iconic sights as the Half Dome and El Capitan rock formations and Yosemite falls, remained open, clear of smoke and free from other signs of the fire that remained about 20 miles away. 
 
 But the blaze was reverberating around the region. It brought a governor's declaration of emergency late Friday for San Francisco 150 miles away because of the threat the fire posed to utility transmission to the city, and caused smoke warnings and event cancellations in Nevada as smoke blew over the Sierra Nevada and across state lines. 
 
 And the fire had established at least a foothold in Yosemite, with at least 17 of its 196 square miles burning inside the park's broad borders, in a remote area near Lake Eleanor where backpackers seek summer solace. 
 
 Park spokeswoman Kari Cobb said that the park had stopped issuing backcountry permits to backpackers and had warned those who already had them to stay out of the area. 
 
 She emphasized that the skies over Yosemite Valley were "crystal clear," however. 
 
 "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." 
 
 The blaze did, however, pose a threat to the lines and stations that pipe power to the city of San Francisco, so Brown, who had declared an emergency for the fire area earlier in the week, made the unusual move of doing the same for the city across the state. 
 
 San Francisco gets 85 percent of its water from the Yosemite-area Hetch Hetchy reservoir that is about 4 miles from the fire, though that had yet to be affected. But it was forced to shut down two of its three hydroelectric power stations in the area. 
 
 The city has so far been able to buy power on the open market and use existing supplies, but further disruptions or damage could have an effect, according to city power officials and the governor's statement. 
 
 The declaration frees funding and resources to help the city and makes it eligible for more federal funds to help with power shortages and outages or water problems. 
 
 The 196-square-mile blaze was 5 percent contained and more than 2,000 firefighters were on the lines. 
 
 It continued to grow in several directions, although "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 Nevada smoke forced officials in several counties to cancel outdoor school activities and issue health advisories, especially for people with respiratory problems. 
 
 The fire was threatening about 5,500 residences, according to the U.S. Forest Service. The blaze has destroyed four homes and 12 outbuildings in several different areas. 
 
 The blaze closed a 4-mile stretch of State Route 120, one of three entrances into Yosemite on the west side. Two other western routes and an eastern route were open. 
 
 Officials issued voluntary evacuation advisories for two new towns _ Tuolumne City, population 1,800, and Ponderosa Hills, a community of several hundred _ which are about five miles from the fire line, Forest Service spokesman Jerry Snyder said. 
 
 A mandatory evacuation order remained in effect for part of Pine Mountain Lake, a summer gated community a few miles from the fire. 
 
 "It feels a little bit like a war zone, with helicopters flying overhead, bombers dropping retardant and 10 engine companies stationed on our street," said Ken Codeglia, a retired Pine Mountain Lake resident who decided to stay to protect his house with his own hoses and fire retardant system. "But if the fire gets very hot and firefighters evacuate, I will run with them." 
 
 Officials previously 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 filled with tourists, the streets are now swarming with firefighters, evacuees, and news crews, said Doug Edwards, owner of Hotel Charlotte on Main Street. 
 
 "We usually book out six months solid with no vacancies and turn away 30-40 people a night. That's all changed," Edwards said. "All we're getting for the next three weeks is cancellations. It's a huge impact on the community in terms of revenue dollars." 
 
 The fire is raging in the same region where a 1987 fire killed a firefighter, burned hundreds of thousands of acres, and forced several thousand people out of their homes. ||||| GROVELAND, Calif. — On Day 10 of the Rim fire — even as the blaze scorched its way deeper into the northern end of Yosemite National Park — firefighters got their first small break Monday against massive forces of nature. 
 
 As the fire reached higher elevations, climbing out of steep ravines, crews could take their stand on more level ground. Huge air tankers could finally drop retardant on accessible ridges. 
 
 The fire has charred a swath of nearly 161,000 acres — including about 21,000 acres inside the park. It has destroyed at least 23 structures, and threatens two groves of giant sequoias and historical structures in the famed park. But about 25 miles away, the tourist magnet of Yosemite Valley remained safe, surrounded by its famed granite walls. 
 
 The fire is burning hotter and faster than any in modern Sierra Nevada history, firefighters say. Officials say it is the California wildfire they have warned about for years, as modern firefighting techniques have snuffed out forest fires, allowing fuel to build up on the mountain floor. 
 
 "This is it. This is the big one," Yosemite Fire Chief Kelly Martin said. 
 
 Yet containment reached 20% — up from 7% Sunday. 
 
 "The fire will burn until the snow flies," said Tom Medema, a Yosemite National Park interpretive ranger. "But today, we finally had a chance to box it in." 
 
 The most hopeful sign was written in the sky. 
 
 For the last week, each afternoon has brought a towering plume of smoke rising over the flames. Inside the plume are lightning and hail, and when the plume collapses, it sends wind pushing the fire in all directions. They call from noon to 5 p.m. the burning hours. 
 
 On Monday, the weather changed slightly — an inversion layer kept the smoke thick and low just a little longer — but it was enough to chop the plume down to half its size. 
 
 "Today we can finally fight the fire on our terms, said Gary Wuchner, Yosemite National Park's fire specialist. 
 
 From the Rim of the World vista point on California 120, he looked out over a wide swath of the fire's footprint. 
 
 It's a spot where tourists often pull over to take photos of the Tuolumne River and mountains in the distance. There was a kiosk giving the history of fires in the area, but it burned to the ground this week. Still standing were two stone monuments to firefighters killed in wildfires in the area — one in 1987, one in 2004. 
 
 "This is hallowed ground to firefighters," Wuchner said. "We have bad history here." 
 
 The needles on four nearby Ponderosa pines were swept straight back, frozen in the direction the fire pushed them. Far off to the northeast, smoke rose above the Hetch Hetchy Reservoir and around Pilot Peak, a fire lookout tower that is staffed each summer. Due north, the edge of Jawbone Ridge looked like it had been outlined with a black marker where the fire had first spilled over. 
 
 Power lines stretched overhead from still standing towers. But the electricity had been cut. On a hill above the river was the only circle of green in sight: Drew Meadow, the base camp for more than 2,000 firefighters. It has now been attacked by the fire from three sides. 
 
 Wuchner's radio crackled constantly. 
 
 "Need retardant drops immediately," a voice said. 
 
 The fight at the park is to save a historic ranger station, stables, lakeside campsites and two groves of giant sequoias. The ancient trees have withstood many fires over the centuries. 
 
 The fear is that this fire, with so much unnatural fuel sending flames higher, could get to the top of the trees and kill them. Wuchner said they had sprinklers dampening the tops of the sequoias and had wrapped all nearby structures in fireproof material. They do not use fire retardant in the national park. When there are lightning fires within the park's boundaries, officials let them burn, unless they are threatening communities. 
 
 "When it comes to fighting the fire within the park," Wuchner said, "what we're banking on is all the fires that came before." 
 
 diana.marcum@latimes.com 
 
 samantha.schaefer@latimes.com 
 
 joseph.serna@latimes.com 
 
 Times staff writer Robert J. Lopez in Los Angeles contributed to this report. Marcum reported from Groveland, Schaefer and Serna from Los Angeles.
– The wildfire threatening Yosemite National Park is throwing so much smoke into the air that it is significantly hurting the air quality in Nevada—more than 100 miles away. Reno and Carson City issued emergency warnings over the smoke from the Rim Fire, and school children were kept inside for the second time in a week to avoid it, the AP reports. The air quality index even briefly passed the rare "hazardous" level. "It's five hours away," says one shocked resident. "I can't run. I can't breathe. It makes me sneeze." The fire is about 20% contained, but almost all of that progress has come at its southwest edge, the LA Times reports. On the east, it has a relatively flat, direct path deeper into Yosemite. "There's not a lot of real good areas to get out in there and do a lot of work," says one US Forest Service official. Meanwhile, state officials are urging residents to be wary of social media, where false rumors are spreading like, well, wildfire. Recently, for instance, "news" spread that the Groveland firehouse had burned down, which "would be a surprise to the firefighters sleeping there," a local sergeant tells the Modesto Bee.