Sacramento this morning with SFD companies on the scene investigating prior. At least one Firefighter was transported with injuries. 0947 hours received a call from a neighbor about a possible gas leak at a vacant dwelling., then at 0951 a chief and a company arrived and minutes later, Pacific Gas and Electric Co. was called to investigate. But within two minutes, the house exploded into a ball of fire splintering the roof upward beyond the trees. At least 4 firefighters were injured.