( CNN ) -- It was a rare bright spot on an otherwise hazy , smoke-filled horizon . An evacuation advisory was lifted Thursday for residents in Tuolumne City , a picturesque community in northern California threatened by an historic wildfire , as firefighters worked to get a grip on the blaze . Known as the Rim Fire , the conflagration has charred nearly 200,000 acres , cost the state more than $ 39 million to date and is threatening 5,500 structures , of which 4,500 are residences . It 's the sixth-largest wildfire in California history . On Thursday , it was in its 12th day and it had only been contained 32 % , according to Cal Fire . Because of the approaching flames , officials have shut down electricity generators , and San Francisco -- more than 120 miles to the west -- temporarily is getting power from elsewhere . While the Yosemite Conservancy says the Rim Fire has consumed tens of thousands of acres inside Yosemite National Park , it has so far had little or no direct impact on Yosemite Valley , a popular spot for tourists and home to many of the park 's iconic attractions , including the El Capitan rock formation . Firefighters hope to keep it that way . Nearly 5,000 people have been assigned to the blaze . `` This is going to be a tough fire , '' said Tom Tidwell , chief of the U.S. Forest Service . `` It 's going to continue for a few more weeks . '' 'It looked like a thunderhead cloud , but it was smoke ' The blaze has created challenges not only to firefighters and utility providers , but also to people who were in the park on long-planned explorations and expeditions . That group included people such as David Hermanson and his friends . They were on a 10-day trek through the wilderness , just four guys and six llamas . Expecting to commune with nature , they instead faced its sheer , raw power when their hike was cut short by the huge wildfire ravaging northern California . Hermanson , a 30-year-old artist and air conditioner repairman from the San Diego area , knows Yosemite National Park like the back of his hand . `` Me and my dad have been hiking Yosemite every year since I was seven , '' he said . Stoked to be back in the park again , Hermanson and three of his buddies loaded up the llamas and embarked August 20 on what was to have been a 60-mile hike from Leavitt Meadows to Lake Eleanor . The group was at Dorothy Lake -- about halfway into their trip -- when clouds started to roll in . At least that 's what they seemed to be . `` It looked like a thunderhead cloud , but it was smoke , '' Hermanson said . `` It was just amazing . It looked surreal . '' Wildfire threatens 90-year-old cabin . Time to turn around . Hermanson used a satellite phone to call his dad , who kept the group apprised as the wildfire gobbled up acres by the thousands . `` It was pretty bad in the evening , '' Hermanson said . `` You could n't see the other side of the lake , the visibility was maybe 100 yards . '' Dad said it was time to turn around . The fire was spreading to the end of the trail . `` We did n't feel endangered , '' a disappointed Hermanson said . `` We were just engulfed with smoke . It seemed like the smoke got worse as it progressed . '' What you need to know about wildfires . ' A lot of work to be done ' Authorities say the Rim Fire started on August 17 . The cause is under investigation . `` There 's a lot of concern , and there 's a lot of work to be done , '' U.S. Forest Service spokesman Lee Bentley said . Firefighters have been able to build fire lines in several locations , officials say . The forecast is looking favorable as daytime highs sink into the 70s over the Labor Day weekend , a break from the temperatures in the high 80s firefighters were facing Wednesday . More than 20 helicopters and air tankers were aiding the efforts . Truck burns . Herman says the group 's decision to abort their hike was a good one . The rendezvous truck they had left at the end of the trail was nothing by a burnt shell after the fire roared through Lake Eleanor . The group made it out safely on Monday . Hermanson 's dad provided the ride home for the crew . And the llamas ? `` They were sneezing a lot . I think they may have been bothered by the smoke . '' Yosemite fire : Blaze spreads to national park . CNN 's Dana Ford , Gary Tuchman and David Simpson contributed to this report .
NEW : The Rim Fire , which has burned nearly 200,000 acres , is 32 % contained . ` ` It looked like a thunderhead cloud , but it was smoke , '' hiker says of fire 's origin . Blaze has cost more than $ 39 million to contain . Forest Service chief says firefighting will continue for weeks .