HONDA ACCORD GOING 45 MPH WAS STRUCK ON LEFT REAR BY ANOTHER CAR GOING ALSO FORTY 45 MPH HITTING GAS TANK LOCATED BEHIND LEFT BACK PASSENGER DOOR. CAR INGNITED UNDER CAR AS CAR WAS SPINNING FOR AT LEAST ONE MINUTE. FIRE BURNED THOURGH BACKSEAT IGNITING SEAT AND SEATBELT TENNSIONIERS.CAR DOORS DID NOT OPEN BUT WINDOWS WERE DOWN. ONE ADULT TWO CHILDREN WERE PASSENGERS,ONE CHILD SUFFERED SECOND AND THIRD DEGREE BURNS FROM BEING IN BACK SEAT. OLDER BROTHER EXTRICATED GRANDMOTHER AND YOUNGER SISTER FROM BACKSEAT OF BURNING CAR OUT OF RIGHT FRNOT PASSENGER WINDOW.AK