WHILE BRAKING THE BRAKE PEDAL WAS WORKING NORMALLY THEN SUDDENLY WENT SOFT. PUMPED BRAKES BUT PEDAL WENT TO FLOOR. CAUSED CAR TO CRASH INTO VEHICLE IN FRONT OF IT. FAILURE WAS CONSISTENT WITH EITHER MATER CYLINDER FAILURE OR HYDRAULIC BRAKE LINE FAILURE CAUSING LOSS OF FLUID AND PRESSURE. BOTH VEHICLES WERE A TOTAL LOSS. BOTH FRONT AIRBAGS WENT OFF IN SUNFIRE. NO SERIOUS INJURIES. *TR