Authorities in the western U.S. state of California say firefighters have contained 20 percent of a massive wildfire that is threatening a famous national park.
The U.S. Forest Service said Tuesday firefighters in the so-called Rim Fire's northwestern part have successfully laid down a dozer line, which exposes the topsoil and prevent fires from spreading. The Rim Fire stretches more than 652 square kilometers.
Nearly 3,700 firefighters have been deployed to battle the blaze, which has consumed more than 72,000 hectares of land, including part of Yosemite National Park. Their efforts have been hampered by strong winds, high temperatures and extremely dry conditions.
The massive fire has destroyed at least two dozen homes and businesses. It is also threatening the reservoir that provides drinking water for the nearby city of San Francisco. Mandatory evacuations are in place in at least two areas.
The reservoir is also the source for three hydroelectric generating stations that supply electricity for San Francisco's public facilities. City officials shut down the generators last week, and are buying electricity from other sources to make up the difference.
The cause of the fire that broke out August 17 is under investigation. It is one of about 50 large wildfires burning in the western United States, which has been plagued by a lack of snow and rainfall this year.