A huge gas-line explosion rocked a neighborhood in San Bruno, outside San Francisco, sparking a fire that killed at least four people and injured more than 52 others. Fanned by the wind, the blaze razed 38 homes and seriously damaged seven more Thursday evening. Several other homes sustained less serious damage. The fire started when a Pacific Gas and Electric Co. gas line suddenly erupted into a geyser of flames, creating a giant crater in the middle of the street. The noise was heard for miles, with many mistaking it for a particularly violent earthquake. "The initial explosion was just deafening," one observer said. The central ball of fire abated late in the night, though firefighters still had trouble reaching it. "We could not get close to the line," a local fire chief said late Thursday. "We are still not able to access the area fully." More than 12 hours after the explosion, the blaze was still only 75 percent contained.