INDIAN FALLS, Calif.—California’s largest wildfire merged with a smaller blaze and destroyed homes in remote areas with limited access for firefighters, as numerous other fires gained strength and threatened property across the U.S. West. The massive Dixie Fire, which started July 14, had already leveled over a dozen houses and other structures when it combined with the Fly Fire and tore through the tiny Northern California community of Indian Falls after dark Saturday. An updated damage estimate was not available Sunday, though fire officials said the blaze had charred nearly 298 square miles (772 square kilometers) of timber and brush in Plumas and Butte counties. It was 21 percent contained. Firefighters carrying hand tools were forced to hike through rugged terrain where engines can’t go, said Rick Carhart, spokesman for the California Department of Forestry and Fire Protection. “It has been burning in extremely steep canyons, some places where it …