Hazardous gas leak forces San Francisco evacuation

A contractor's drill pierced a gas main and sent choking yellow-brown gas laced with hazardous PCBs (polychlorinated biphenyls) through the heart of the city's financial district, forcing the evacuation of tens of thousands of office workers and shoppers Tuesday.

The gas shot like a geyser from a 16-inch pipeline for 2 1/2 hours, coating a square block of balconies, sidewalks, streets, and parked cars with a gooey oil before Pacific Gas & Electric Company crews were able to stem the flow. Traces of the gas, however, continued to leak into the air until late in the night, when crews were able to seal the leak.

Despite the dangers of the PCBs, the city escaped the threat of an explosion and fire, said fire officials.