Boxer joined other federal, state and local officials this morning on a tour of the Crestmoor Canyon site where, at about 6:15 p.m. Thursday, a 30-inch PG&E steel gas transmission pipeline ruptured, causing a massive explosion and fire that killed four people and hospitalized 52 others.
Two others are still unaccounted for, Boxer said at the news conference following the tour of the site, where 37 homes were destroyed and eight sustained major or minor damage.
Authorities did not immediately release information on the two people who are still missing.
Boxer said the disaster was "a heartbreaker" that "raises a lot of questions" about the safety of other pipelines in residential areas.
The senator said the investigation, led by the National Transportation Safety Board, will "check if there was adequate maintenance on the pipeline, and any recent excavation on the pipeline," as well as "if PG&E had an emergency plan to respond to this, and how it was carried out."
Boxer called for the "need to accelerate inspections" of other pipelines in residential and urban areas around the state.
"I have to be very clear that we're trying to prevent this from ever happening again," she said.
Boxer said she was told by PG&E that customers who are worried about pipelines in their area can call the utility and will be told where the nearest ones are.
PG&E President Chris Johns was also at the news conference, and said that the utility "will do what's right for the folks to help this community."
Johns addressed reports that residents smelled natural gas in the days and weeks prior to the explosion, and said officials have not found any records of calls to PG&E about a problem in the first nine days of September, or a record of their crews being in the area.
The California Public Utilities Commission has established a toll-free number and e-mail address for people to say if they noticed the smell prior to the explosion.
People can call (800) 789-0550 or send an e-mail to SBFire@cpuc.ca.gov.