A Structure fire came in at 0430 of reports that a garage was on fire.  Truck 6 was the first unit on scene and reported there were two single family dwellings involved. There was some uncertainty if all parties were out of the homes. Truck 6 was staffed with 4 personnel made the decision to split the crew and search both structures for victims at the same time. Home number one was found to be evacuated. When the other crew entered home two they found LIGHT smoke about 1′ off the celling, They preformed a search on the first floor then the 2nd with no one found inside. As they hit the top of the landing the rooms below flashed and became fully involved causing a chimney effect to where they were located. It is believed there was a natural gas explosion causing the flash. The fire had immediately melted the lapels (that did trigger a emergency tone) and the radios became inoperable.  This flash also melted many of the straps holding on the SCBA along with other parts of the gear. It is believed one firefighter was disoriented and had to be thrown down the stairs and out of the structure.  As they started to take off the gear they found that much of their skin remained inside their gloves and were transported to a hospital.