Could negligence have led to the fire in San Bruno, the San Francisco suburb where at least four people have died and dozens of homes have been destroyed? Residents of the town say they began smelling natural gas a week ago. Local residents say the utility PG&E visited the neighborhood last week and told people to shut their garage doors and to stay inside. The fire began on Thursday when a natural-gas line erupted, shooting a fireball more than 1,000 feet in the air. So far, the fire has spread to 15 acres.