Investigators in San Francisco are today trying to determine the cause of the devastating blast that claimed the life of six people and injured 50 more after a natural gas pipeline exploded.
More than 50 buildings were razed to the ground after the massive explosion triggered intense fires which tore through the San Bruno suburb.
Around 39 people were injured by the blast and flames were visible several miles away from San Francisco International Airport.
San Bruno Fire Captain Charlie Barringer told the L.A. Times: 'I thought a 747 had landed on us. It shook our station right to its foundation.'
Lt. Gov. Abel Maldonado, serving as acting governor while Gov. Arnold Schwarzenegger is in Asia, declared a state of emergency in the Crestmoor district and said the blaze was 75% contained.
'We don't know what caused [the rupture], we will find out soon,' Maldonado said in a news conference near the scene.
Fireball plumes from rises from a San Francisco surburb after a gas explosion killed one person injured 25 people.
Just charred blackened trunks of trees give indication of the forestation once stood.
Remnants of charred chimney stacks are all reminded of homes in the streets in San Bruno.
Torched: It is unclear what caused the explosion, but Pacific Gas & Electric Co said one of its pipes was ruptured
'There's a lot of devastation in homes, obviously vehicles. The streets are just gone, and all you see are fireplaces standing straight up. It's a horrible tragedy for the people of San Bruno.
Rick Bruce, 54, a retired police officer who has lived in the neighbourhood since 1980 said the destruction looked like a war zone.
'People want to see if their houses burned down. I was lucky to get in last night. Most people had to leave within 45 minutes, so they saw the flames but didn't know whether their house burned. The fire looked like London during the Blitz.'
In minutes after the explosion, he talked to 911 dispatchers who said they were still trying to find the site.
'At 20 minutes, there was no fire, no police. I was furious. I said, 'There's nothing! We're standing in the street looking at the biggest fire I've ever seen in my life and there's no one here.'
San Bruno Mayor Jim Ruane said, 'The sun is shining over there, but there's still a dark cloud over this city'.
Brothers Bob and Ed Pellegrini, whose homes were near the centre of the explosion told The Oakland Tribune that they thought an earthquake had struck until they looked out of their window.
'It looked like hell on earth. I have never seen a ball of fire that huge.' Bob Pellegrini said.
His brother Ed shared their grief, 'The house is gone. I have nothing. Everything is gone. We're homeless.'
The initial explosion was heard from miles away and shot a fireball more than 1,000 feet into the air. Flames reached as high as 100 feet as the fire fueled itself on burning homes.
Kelly Huston, an assistant secretary with the California Emergency Management Agency, told KTLA TV: 'We have confirmed that there are 53 structures, those are mostly homes, that were lost, about 120 damaged.' The injured people have been taken to hospitals with special burn treatment units.
Most of the burned buildings were homes in a densely populated residential area, officials said.
The gas line belongs to the northern California utility Pacific Gas & Electric Co.
A statement from the company said: 'Though a cause has yet to be determined, we know that a PG&E transmission line was ruptured.
'If it is ultimately determined that we were responsible for the cause of the incident, we will take accountability.'
Resident Connie Bushman returned home to find her block was on fire. She said she ran into her house looking for her 80-year-old father, but could not find him.
'I don't know where my father is, I don't know where my husband is, I don't know where to go,' she said.
Judy and Frank Serrsseque managed to escape the flames with a makeshift wagon carrying important documents, medication and their three cats.
Mrs Serrsseque said she heard the blast and saw the flames were being blown towards their home.
'We got everything together, and we just got out. Mostly we're wondering if we have a house to go back to.'
Sergio Campos, 21, said he was on his way to class at Skyline College when he saw the fire and pulled over. Even from a distance, the blaze 'sounded like a big, ongoing roar,' he said.
'A lot of us were confused because we didn't know if it was a natural explosion or an airplane crash,' he told CNN.
The explosion of the high-pressure gas line occurred during rush hour at around 6pm local time.
Water-dropping aircraft have assisted up to 200 firefighters in tackling the blaze, which was spread quickly through high winds.
Broken water lines have hampered the effort after the explosion destroyed hydrants near the blast scene.
Dennis Haag, chief of San Bruno Fire Department, said: 'The fire is being contained at this point... it is around 50 per cent contained.'
Television footage showed a massive fireball and flames shooting skywards.
People living in the area said they thought the loud boom caused by the blast was the result of an earthquake or a plane crash.
Around 100 people have spent the night at an evacuation centre.
California Lieutenant Governor Abel Maldonado, serving as acting governor while Arnold Schwarzenegger is on a trade mission to Asia, has declared a state of emergency to free up state assistance for local government.
Homes totally destroyed in the gas explossion cause by underground gas pipe ruptured.
Only chimneys reminded after the huge fireballs and fire engulfed the homes in streets of San Bruno
Gaping hole, fire investigator search a massive hole at the centre of the gas pipe rupture that flattened a surburb in San Bruno.Charred building reminds nearby,
53 buildings destroyed by the explosion or scores of fires triggered by the burning debries.
All nighter as fire fighters tackle the fire all night.
Firefighter so far managed to contain 50 per cent of the fire.
Police officer retreat from very hot flames casuse by underground gas explosions.
