In the United States, at least six people have been killed when a gas pipeline exploded and set off a fire at the town of San Bruno near San Francisco.San Bruno Fire Captain Charlie Barringer said he expected the toll to rise as more homes were searched. More than 100 residents were forced to flee and about 170 homes damaged as the blast ripped through the town triggering a giant fire. California's acting governor Abel Maldonado declared a state of emergency for the city just three kilometres west of the San Francisco International Airport.