A 300-acre fire in the El Dorado National Forest has forced authorities to close a stretch of the main route to South Lake Tahoe through the night. The California Highway Patrol says U-S Highway 50 is closed between Pollock Pines and South Lake Tahoe. The CHP responded to the blaze around four yesterday afternoon. California forestry department spokeswoman Teri Mizuhara says more than 300 firefighters are on the scene. She says the fire has caused trees and rocks to crash down hills and onto the highway. Investigators aren´t sure what started the blaze.