Fire crews are still working to douse the blaze and authorities have said there could be other casualties. The number of deaths was rising: San Francisco state Sen. Leland Yee told The Associated Press he was briefed at the scene Friday morning by the California Emergency Management Agency and at least six people have died.
California Lieutenant Governor Abel Maldonado said at a news conference he knew of at least four people killed and more than 50 injured. He said a natural gas line ruptured at 6:24 p.m. Thursday near the blast but they're not yet sure why. The explosion was heard for miles and shot a fireball more than 1,000 feet in the air and sent frightened residents fleeing for safety and rushing to get belongings out of burning homes. The blast left a giant crater and sent flames tearing across several suburban blocks in San Bruno.
After the initial blast, flames reached as high as 100 feet as the fire fueled itself on burning homes, leaving some in total ruins and reducing parked automobiles to burned out hulks. At least 38 homes were destroyed and dozens more seriously damaged, fire officials said early Friday.
The fire had spread to 15 acres and was 78 percent contained late Thursday.
Maldonado, acting governor while Gov. Arnold Schwarzenegger was in Asia on a trade mission, declared a state of emergency in San Mateo County.
Pacific Gas and Electric Co. said in an e-mailed statement that "if it is ultimately determined that we were responsible for the cause of the incident, we will take accountability."
The company said Friday morning a damaged section of a 30-inch steel gas pipeline had been isolated and gas flow had been stopped. About 300 customers were without gas service and about 700 without electricity at 4 a.m. Friday.
The National Transportation Safety Board said Friday that it has sent a four-member team to San Bruno to investigate the blast. The NTSB's duties include investigating pipeline accidents.
Brothers Bob and Ed Pellegrini, whose homes was near the center of the explosion, told The Oakland Tribune that they thought an earthquake had struck until they looked out the window.
"It looked like hell on earth. I have never seen a ball of fire that huge," Bob Pellegrini said.
The flames quickly chased them from their home.
"The house is gone," Ed said. "I have nothing. Everything is gone. We're homeless."
Stephanie Mullen, Associated Press news editor for photos based in San Francisco, was attending children's soccer practice with her two children and husband at Crestmoor High School when she saw the blast at 6:14 p.m.
"First, it was a low deep roar and everybody looked up, and we all knew something big was happening," she said. "Then there was a huge explosion with a ball of fire that went up behind the high school several thousand feet into the sky.
"Everybody grabbed their children and ran and put their children in their cars," Mullen said. "It was very clear something awful had happened."
Several minutes later, Mullen was near the fire scene, about a half-mile away in a middle-class neighborhood of 1960s-era homes in hills overlooking San Francisco, the bay and the airport. She said she could feel the heat of the fire on her face although she was three or four blocks away from the blaze. It appeared the fireball was big enough to have engulfed at least several homes.
"I could see families in the backyards of the homes next to where the fire was, bundling their children and trying to get them out of the backyards," she recounted.
She said people in the neighborhood were yelling, "This is awful" and "My family is down there."