A quick-moving wildfire in the Sequoia National Forest in California had burned more than 1,600 acres by Monday morning, a U.S. Forest Service official said. Forest Service spokeswoman Denise Alonzo said more than 400 firefighters were assigned to the wind-whipped blaze, the Los Angeles Times reported. The George fire was just 5 acres Friday afternoon. Alonzo said the fire was about 35 percent controlled Monday but crews were \"most definitely concerned\" about it spreading further. Authorities closed several roads and trails in the area, and hikers and campers were ushered out, but no structures were endangered, she said. The cause of the fire had yet to be determined.