SAN BRUNO, Calif. — The section of gas pipeline that ruptured and exploded in a suburban San Francisco neighborhood, killing four and injuring nearly 60 others, was ranked as high risk because it ran through a highly populated area, state and federal authorities said Saturday.

One of the victims killed in the inferno Thursday worked for the commission reviewing Pacific Gas & Electric’s investment plans to upgrade its natural gas lines, including another risky section of the same pipeline within miles of her home, a colleague confirmed.

Longtime California Public Utilities Commission analyst Jacqueline Greig and her 13-year-old daughter Janessa died in the massive blast, which left a crater near their house and laid waste to dozens of 1960s-era homes in the hills overlooking San Francisco Bay.

Jessica Morales, 20, was also killed in the explosion and fire. One other victim found earlier hasn’t been identified, and authorities were trying to identify remains found Saturday morning. Two people were still missing from the blast.

Greig spent part of the summer evaluating PG&E’s expansion plans and investment proposals to replace out-of-date pipes, as part of the utility’s overall bid to raise consumers’ rates, co-worker Pearlie Sabino said.

Sabino and Greig were members of a small commission team that advocates for consumer and environmental protections pertaining to natural gas.

“It’s just so shocking because she was one of the ones who was most closely involved with this kind of work,” said Mike Florio, an attorney with the San Francisco advocacy group The Utility Reform Network who worked with Greig. “Little did we know that pipe was near Jackie’s own neighborhood.”

Among the paperwork PG&E submitted for hearings with regulators was a document ranking a section of the same gas line about two and half miles from the blast as within “the top 100 highest risk line sections” in the utility’s entire service territory, documents show.

The federal Pipeline and Hazardous Materials Safety Administration classified the 30-inch diameter transmission line, which ran for about a mile and a half near Greig’s home, as a “high consequence area” requiring more stringent inspections called integrity assessments, agency spokeswoman Julia Valentine said. Nationwide, only about 7 percent of gas lines have that classification, she said.

The state commission gave that section of pipe the same classification and had conducted audits on that stretch, spokeswoman Terrie Prosper said. PG&E also had conducted leak surveys, evaluations and patrols on the gas line, she said.

Saturday, Lt. Gov. Abel Maldonado, who is serving as acting governor while Gov. Arnold Schwarzenegger travels in Asia, directed the commission to perform integrity assessments of all pipeline segments located in the impacted area.

Maldonado also ordered further inspections and surveys for high consequence areas, including a detailed inspection of three transmission lines that run through San Mateo County.

A group of local, state and federal officials toured the damaged area Saturday and described a ghost-town full of remnants of cars melted in driveways and pieces of houses, some left with just the chimney standing.

Besides the 40 homes leveled by the blast, seven were severely damaged, while dozens of other houses suffered less severe damage in the fire that sped across 15 acres.

Residents of roughly 270 homes that have been off-limits following the blaze will be allowed to return for good starting around noon on Sunday, San Bruno City Manager Connie Jackson said. Some residents were authorized to enter a limited area Saturday to retrieve belongings.

Michelle Salinda’s home was destroyed in the fire, but her husband, Ricardo, and 15-year-old son were able to escape. She said she wants to return to what’s left of her home to find closure.

“I can’t wait to see it, even though it’s all destroyed, because I know that’s where I am going to start again,” she said.

Ricardo Salinda described a harrowing scene as he and his son escaped from a 200-foot fireball racing toward the front door of their home. The two suffered burns as they fled the flames.

They used a ladder to scale a neighbor’s fence but it was too hot there, and Salinda said he lifted his 120-pound son over the next fence and scrambled after him.

“I don’t know how I was able to lift him,” he said. “It’s a blessing we got out.”

___

Contributing to this report were video journalist Haven Daley in San Bruno and John S. Marshall and Sudhin Thanawala in San Francisco. Burke reported from Fresno, Calif.