The San Francisco Chronicle says the rupture occurred during a pressure test Monday south of Bakersfield as the company was planning to boost gas levels on the pipeline to meet winter demand.
The newspaper says the line failed during a spike test on one of two parallel transmission pipes that run to a major PG&E terminal in Milpitas and provide much of the Bay Area's natural gas.
The testing was part of the utility's effort to assure that its gas system is safe in the aftermath of last year's deadly pipeline explosion in San Bruno.
PG&E officials say did not have a timetable for repairs would be made.
