The wildfire threatening Yosemite National Park has grown to become California's seventh biggest ever, as firefighters battle to protect San Francisco's main water supply.
The so-called Rim Fire now covers some 184,000 acres (73,000 hectares) -- an area bigger than Chicago -- and was still only 20 percent contained by Tuesday, albeit up from 15 percent a day earlier.
A main road into Yosemite, one of America's top tourist destinations, remains closed as more than 4,081 firefighters battle the flames. The cost of the fire has reached $33 million.
VIDEO: California Wildfire Whodunnit
"It's burning its way into the record books," Daniel Berlant, a spokesman for the California Department of Forestry and Fire Protection, or Cal Fire, told the Los Angeles Times.
The blaze has forced the closure of multiple roads, campgrounds and other facilities in the area, and has also threatened a number of groves of giant sequoia trees, some of the biggest and oldest living organisms on the planet.
It remains more than 15 miles away from the majestic Yosemite Valley area at the heart of the park, visited by millions of tourists every year to see natural wonders including the Half Dome and El Capitan rock formations.