MY WIFE AND I HAD JUST GOTTEN INTO THE TRUCK. WHEN I STARTED IT AND PUT IT IN DRIVE, A VERY LOUD EXPLOSION OCCURRED. MY WIFE HAD ALREADY FASTENED HER SEAT BELT BUT I (DRIVER) HAD NOT. SHE THOUGHT THAT SHE HAD BEEN SHOT. BOTH SEAT BELT PRETENSIONERS HAD EXPLODED. THE AIRBAG LIGHT CAME ON AS DID THE EMERGENCY FLASHERS. BOTH SEAT BELTS ARE INOPERABLE.