Emergency officials have confirmed that six people were killed in a huge explosion and resulting fire south of San Francisco, a California state senator said Friday. Senator Leland Yee said he was briefed Friday morning by the state's Emergency Management Agency. Earlier, California Lieutenant Governor Abel Maldonado told a news conference that at least four people were killed and more were injured. Thursday night's explosion was heard for kilometers and shot a fireball 300 meters in the air, causing frightened residents to flee for safety and rush to get valuable belongings out of burning homes.