A brush fire in the Sierra National Forest exploded Saturday, consuming more than 36,000 acres and threatening numerous mountain communities.
The fast-moving fire cut off evacuation routes, trapping people near Mammoth Pool Reservoir, Sierra National Forest spokesman Dan Tune said.
He could not provide the number of people trapped near the popular recreation site or confirm reports that they were advised to jump into the reservoir if necessary. But he said people have been advised to shelter in place while strike teams of engines and hand crews race to the area to battle the flames.
The blaze is still zero percent contained. Tune said firefighting resources _ "as much as we can spare" _ are being redeployed to the area.
The fire is also threatening a number of structures and power lines.
"The priority right now is community and life safety," he said.
Residents of Huntington Lake, Camp Sierra and Big Creek in Central California were ordered to evacuate, and portions of Highway 168 were shut down, the Fresno County Sheriff's Office said. Shaver Lake was closed.
Later Saturday afternoon, evacuation orders were issued for the Kinsman Flat area in North Fork, the Madera County Sheriff's Office said. Deputies were going door to door notifying residents of the danger. The Rock Creek and Fish Creek campgrounds were also being evacuated, officials said.
In total, about 2,000 structures were threatened, authorities said.
The American Red Cross was setting up a temporary evacuation point at Foothill Elementary School in Prather. A second temporary evacuation point was being established at North Fork Elementary in North Fork.
The Creek fire started about 6:45 p.m. Friday in the Big Creek drainage between Shaver Lake, Big Creek and Huntington Lake, the U.S. Forest Service said in a statement.
It had grown to about 2,000 acres by Saturday morning and by the afternoon, it was at 5,000 acres, officials estimated. The fire was zero percent contained.
About 450 firefighters were fighting the blaze with 20 engines, two helicopters and three air tankers, the Forest Service said. There was no word on how it started.
The fire was burning in steep and rugged terrain amid high temperatures, with much of the region in the grips of a potentially record-breaking heat wave.
Authorities were asking that anyone scheduled to visit the area during the holiday weekend to make alternate plans.