SAN FRANCISCO A wildfire raging out of control near Yosemite National Park in northern California ballooned to nearly 54,000 acres on Thursday, more than tripling in size from the day before, forest officials said.
The blaze, which is burning mostly in Stanislaus National Forest and has destroyed two homes and seven outbuildings since it broke out on Saturday, was only 2 percent contained despite efforts of more than 1,360 firefighters to tame it, said U.S. Forest Service spokesman Trevor Augustino.
Augustino said the Rim Fire, named after a popular local lookout point, Rim of the World, is burning on rugged and remote terrain, which has made it challenging for firefighters to haul in hoses to damp the flames.
"The terrain is so difficult that you can't go into direct attack," Augustino said, adding that he expected a lot more firefighters to arrive on Friday as reinforcements.
The Rim Fire is the fourth-largest and fastest growing wildfire in the nation, said National Interagency Fire Center spokeswoman Robyn Broyles. It is one of 50 large wildfires burning throughout the U.S. West.
On Wednesday, the fire had been 5 percent contained and ranged across only 16,000 acres, but it grew dramatically overnight and the containment level fell.
Two evacuation centers have been set up for residents in the area, Augustino said.
Residents have been urged, but not required, to leave their homes if they have health conditions that could be affected by the rising level of smoke in the air, Augustino said. He said he did not know how many residents had chosen to evacuate or were using the shelters.
"There are a lot of little pockets of residences throughout this area," he said, adding that the fire has started to spread to private land and was roughly five miles from the northwest outer edge of Yosemite National Park.
Yosemite National Park, spanning 750,000-acres and best known for its waterfalls, attracted nearly 4 million visitors in 2012, according to the park website.
Park officials on Tuesday were forced to stop westbound traffic on Highway 120, one of four access routes to the park, due to the fire. But they have no immediate plans to close the park, said Yosemite park ranger Scott Gediman. He added that the sky was clear and free of smoke over Yosemite on Thursday.
The cause of the Rim Fire is unknown and under investigation, Augustino said
(Editing by Alex Dobuzinskis, Cynthia Johnston and Steve Orlofsky)