Companies operating natural gas transmission pipelines reported an average of one death per year from 2004 to 2008,the report said.
The Department of Transportation, it noted, reported 63 natural gas transmission pipeline accidents in 2008.
But San Francisco-based Pacific Gas and Electric, the company whose ruptured pipeline led to the San Bruno explosion, was also culpable in at least one other recent deadly incident, documents show.
An explosion and ensuing fire caused by a natural gas leak destroyed a house in December 2008 in Rancho Cordova, California, near Sacramento, according to the National Transportation and Safety Board.
One person died and five other people, including one utility worker and a firefighter, were injured.
PG&E had been notified of the gas leaks at the house where the blast occurred, according to the safety board's accident brief. Crews arrived to address the situation and a foreman had just finished speaking with a resident at the house and was about to investigate further when the explosion happened.
Sunny Dickson, identified by the Sacramento Bee as the granddaughter of the man who died, told the Sacramento Metropolitan Fire District that the family had returned home around noon on Christmas Eve, according to the safety board's brief.
The PG&E technician had knocked on their door earlier but did not see when the family returned.
Dickson said she did not see any PG&E vehicles nearby nor any warning notice on the door telling the family not to enter until leak investigators checked for gas.
Dickson went into the bathroom and soon after she heard a "whoosh" and two explosions, the safety board brief said. She escaped to the street with severe burns, as did her mother. Her grandfather, Wilbert Paana, died.
