(Updates acreage, adds injuries)
By Madeleine Thomas
SAN FRANCISCO, May 27 (Reuters) - A wildfire burning west of Yosemite National Park in central California threatened more than 100 homes on Tuesday as it raged out of control in brush left bone dry by severe drought, state fire officials said.
California's fire season has been particularly severe this year, with one of the worst droughts in the state's history playing a key role in the size and number of wildfire outbreaks.
The blaze that erupted on Monday afternoon has already charred more than 1,300 acres (526 hectares) and was burning on the southeastern shores of Lake McClure in Mariposa County, according to the California Department of Forestry and Fire Protection.
Five firefighters have been injured battling the blaze, including one who suffered serious lacerations in a chainsaw accident, said Cal Fire spokesman Daniel Berlant.
That firefighter was taken to hospital, Berlant said, but his condition was not known. Injuries to the other four were minor, he added.
More than 100 homes were ordered evacuated ahead of the flames, which were only 20 percent contained as of Tuesday evening, Berlant said.
More than 670 firefighters were working to contain the blaze, including crews from Cal Fire, the U.S. Forest Service, the Bureau of Land Management and dozens of local fire aids.
Six air tankers and several helicopters have been brought in to fight the fire from the air, besides crews on the ground building containment lines and putting out hot spots, Berlant said.
Since Jan. 1, Cal Fire has responded to more than 1,500 wildfires, nearly double its five-year average over the same period. The department has hired additional seasonal firefighters across the state and bolstered fire gear earlier in the season than usual.
"The fire is still under investigation so we haven't determined exactly what sparked it, but the drought is affecting how quickly it's been able to grow," Berlant said.
"These are conditions we would typically see in the summertime because the grass and the brush are just so dry. We are making progress despite how dry and fast moving this fire is." (Additional reporting by Curtis Skinner; Editing by Dan Whitcomb, Steve Orlofsky and Clarence Fernandez)