AFTER WHAT WAS DESCRIBED AS A NORMAL LANDING LIQUID PROPANE BEGAN ESCAPING. THE PROPANE VAPORIZED & WAS IGNITED ENGULFING THE GONDOLA IN FLAMES. FOUR PAX EXITED THE GONDOLA WHILE IT WAS STILL ON THE GROUND & THE LAST SURVIVOR EXITEDAT ABOUT 25 FT AS THE BALLOON BEGAN RISING. THE REMAINING 4 PAX BEGAN JUMPING OR FALLING FROM THE GONDOLA AT ABOUT 100 FT WITH THE LAST EXITING AT AN ESTIMATED 600 FT AGL. THE BALLOON CONTINUED TO RISE & AT ABOUT 1,000 FT TWO PROPANE TANKS EXPLODED. THE OWNER/PILOT HAD INSTALLED 6 PROPANE CYLINDERS. A PORTION OF ONE TEE FITTING WAS DETERMINED TO BE BRASS, & ACCORDING TO A METALLURGICAL REPORT THE HOSES USED TO MANIFOLD THE PROPANE CYLINDERS WERE DETERMINED TO BE RUBBER COVERED BY A WOVEN FABRIC. ONLY CADIUM PLATED STEEL FITTINGS & WIRE MESH REINFORCED HOSES WERE RECOMMENDED BY THUNDER BALLOONS,LTD. & AT NO TIME WOULD BRASS FITTINGS & NON-WIRE MESH HOSES BE RECOMMENDED BY THEM.