Updated 1:41 p.m. EST
SAN BRUNO, Calif. - Fire crews tried to douse the remnants of an enormous blaze and account for the residents of dozens of homes after a gas line ruptured and an explosion ripped through in a neighborhood near San Francisco, killing at least four people and likely more.
Emergency workers haven't been able to get into all the homes and authorities said there could be more 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.
Fire officials and Yee later said the official count is still four killed and 52 injured, with three people suffering critical burns in the blaze that enveloped the middle-class neighborhood of 1960s-era homes in hills overlooking San Francisco, the bay and the airport. Four firefighters suffered minor smoke inhalation injuries and were treated and released within a couple hours, said Fire Chief Dennis Haag.
Haag said crews walked through the neighborhood Friday morning and revised the damage estimate to 38 structures destroyed and seven significantly damaged. Dozens of other homes suffered less severe damage in the fire, which burned 15 acres.
The blaze was 75 percent contained by midmorning, officials said.
The explosion was heard for miles and shot a fireball more than 1,000 feet (300 meters) 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.
After the initial blast, flames reached as high as 100 feet (30 meters) 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 10 acres (four hectares) and was 50 percent contained late Thursday, said Jay Allen, spokesman for the California Emergency Management Agency.
California Lieutenant Governor Abel Maldonado, acting governor while Gov. Arnold Schwarzenegger was in Asia on a trade mission, declared a state of emergency in San Mateo County.
"It was like a bomb went off," Maldonado told CNN from the scene early Friday.
He said the cause of the conflagration was still unclear.
Pacific Gas and Electric Co. said Friday morning a damaged section of a 30-inch (76-centimeter) 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.
Associated Press Writers Juliana Barbassa in San Bruno and Marcus Wohlsen, John S. Marshall and Jason Dearen in San Francisco contributed to this report.