RedactedNarrative: OPERATOR OF VESSEL 1 STATED THAT HE WAS LEAVING THE NO WAKE ZONE FROM ROBINSON LANDING TRAVELING SOUTH.  WHEN THE THROTTLE WAS APPLIED, THE BOAT HESITATED AND THEN MADE A LOUD POPPING SOUND FROM THE ENGINE COMPARTMENT.  WHEN THE OPERATOR OF VESSEL 1 TURNED AROUND HE NOTICED A FIRE BALL BY THE ENGINE.  THE PASSENGERS OF THE VESSEL THEN JUMPED INTO THE WATER.  THE OPERATOR USED THE FIRE EXTINGUISHER AND EXTINGUISHED THE FIRE.  THE VESSEL WAS TOWED BACK TO THE BOAT RAMP AT ROBINSON LANDING.  EMS ARRIVED AND TRANSPORTED VICTIMS 1 AND 2 TO COMANCHE COUNTY MEMORIAL HOSPITAL WHERE THEY WERE TREATED AND RELEASED.