At least four people have died in a gas line explosion and fire that destroyed 38 homes in a San Francisco suburb, and officials fear the toll could rise.
The blast tore through a neighbourhood in San Bruno, a small city near San Francisco International Airport, engulfing dozens of houses and vehicles.
Four firefighters were among the 52 injured. Many people were still missing, and San Bruno Mayor, Jim Ruane, said he expected the number of dead to rise.
The explosion shattered water mains, hindering firefighting efforts, and witnesses said it blew a fireball hundreds of metres into the air.
The blast left a large crater, and residents said it was so strong they first thought it was an earthquake or plane crash.
The ruptured pipeline belongs to utility Pacific Gas & Electric Co, which was investigating reports that people had smelled gas prior to the blast.