Utility officials, city leaders and politicians who toured the devastated neighborhood Saturday said a premium is being placed on ensuring the integrity of the gas line and eliminating fear that Thursday's thunderous explosion could be repeated.

PG&E said it is reinspecting all three natural gas transmission lines serving the San Francisco Peninsula.

On Saturday, hundreds of San Bruno residents — some with gauze bandages wrapping their feet and arms — jammed a town hall meeting, expressing frustration and anger at being prevented from returning to their homes. Some were still wearing the smoky clothes they threw on as they scrambled from their burning homes Thursday evening.

But residents also gave a standing ovation to the city's fire and police chiefs and an even warmer reception to news that many residents of the 271 evacuated houses would be allowed to return to their neighborhood Sunday. Residents who live near the blast zone, including those in the 37 destroyed homes, will not immediately be permitted to return.

"In a split second, a flash, our lives changed forever," Mayor Jim Ruane told residents who packed the pews at St. Robert's Catholic Church.

"This has been a tragedy of immense proportion."

San Bruno Police Chief Neil Telford confirmed late Saturday that seven were dead and six were missing. Search-and-rescue crews continued to make their way through the disaster area with cadaver dogs.

Additional reports of missing people were filed Saturday, police said. Police officials said they do not know people are missing until relatives contact authorities to say they can't locate family members.

The San Mateo County coroner's office questioned the police department's body count, saying it has only four bodies. Michelle Rippy, senior deputy coroner, said, "We have four confirmed dead."

Although residents reported smelling gas in the days before the explosion, Johns said the utility had combed through two-thirds of the consumer calls received the week before the blast and found no record of any such complaints. Nor, he said, was there a record of crews responding to the area.

The burst pipeline, which had been installed in 1956, was not uncommonly old, experts said.

"Just like with an old airplane, the key is maintenance," said Christopher Hart, vice chairman of the National Transportation Safety Board.

Although the safety board's final report may take a year or more to complete, Hart said, any findings that merit "urgent attention" will be acted on.

Sen. Barbara Boxer (D-Calif.) said officials would push for "robust inspections" of natural gas lines that pass through residential neighborhoods.

"We cannot wait for the answers to this. Inspections are the way to go," she said. "We have to be very clear that we're trying to prevent this from ever happening again."

As officials worked to secure the area and restore services, people displaced by the explosion were growing increasingly frustrated. "We're trying to get back to our homes, but we're getting the runaround," said Cherie Sekulich, 35, who hasn't been allowed back to her property since flames chased her away and destroyed her backyard deck. "All I could grab was my two cats, my two birds and my dog."