An explosion occurred at 6:11 pm PDT on September 9, 2010, in San Bruno, California, a suburb of San Francisco. Eyewitnesses reported the initial blast “had a wall of fire more than 1,000 feet high”.
The loud roar and shaking led some residents of the area, first responders, and news media to initially believe that it was an earthquake or that a large jetliner had crashed. As of September 29, 2010, the death toll was eight people. The United States Geological Survey registered the explosion and resulting shock wave as a magnitude 1.1 earthquake.
REF: Wikipedia