Blast near San Francisco kills at least four people
At least four people were killed and dozens injured in an explosion and fire near San Francisco, reports say.
The blast tore through a neighbourhood in San Bruno, engulfing dozens of houses and vehicles. It shattered water lines, hindering firefighting efforts.
Witnesses said it blew a fireball 1,000 feet (300 metres) into the air.
Firefighters have contained the blaze but much of the the area is still too hot for them to enter, officials said.
Officials said a natural gas line had ruptured near the scene, leaving a vast crater, but the origin of the explosion remained unconfirmed.
"I thought a 747 had landed on us," firefighter Capt Charlie Barringer told the Los Angeles Times newspaper. "It shook our station right to its foundation."
Capt Barringer said he expected the death toll to rise when firefighters were able to search more destroyed houses.
Carole Zeichick, a San Bruno resident, told the BBC she was watching smoke from her car when the explosion occurred.
"A fireball erupted and we could feel the heat in our car from the roadside," Ms Zeichick said.
San Bruno is a town of about 41,000 people near San Francisco International Airport.
The explosion, which was heard for miles, destroyed a grid of water mains, leaving the fire station without water.
San Bruno Fire Chief Dennis Haag said: "It looked like a broken gas line, high-pressure gas line".
Christopher Johns, president of Pacific Gas and Electric, said the company would co-operate with investigators but emphasised the cause of the fire had yet to be determined.
Near the height of the fire, between 150 and 200 fire fighters were on the scene battling the blaze.
Mr Haag said 53 homes had been severely damaged, with as many as 120 homes suffering some fire damage.
Victims suffering serious burns began arriving in San Francisco-area hospitals shortly after the explosion.