WHILE COMING TOWARDS AN INTERSECTION, THE CAR IN FRONT OF ME HIT HER BRAKES SUDDENLY. I REACTED BY HITTING ME BRAKES AND WHILE I WAS SLOWING DOWN MY BRAKE PETAL SUDDENLY WENT ALL THE WAY DOWN TO THE FLOOR. I WAS TRAVELING APPROX 5-10 MPH WHEN I HIT THE VEHICLE IN FRONT OF ME. AFTER MOVING OUR VEHICLES FROM THE ROAD, I DISCOVERED BRAKE FLUID DRIPPING FROM UNDER MY ENGINE. I INSPECTED THE BRAKE FLUID RESERVOIR AND THE MASTER CYLINDER... BOTH LOOKED NORMAL. I GOT UNDER THE FRONT OF MY TRUCK AND I COULD SEE BRAKE FLUID HAD BEEN SPRAYED ALL OVER THE LOWER FRONT OF THE ENGINE AND FRONT BUMPER. I COULD SEE THAT THE BRAKE LINES WERE VERY RUSTY. BEFORE THE ACCIDENT THERE WASN'T ANY INDICATION THAT I WAS HAVING PROBLEMS WITH MY BRAKES. I SEEMS AS THOUGH THE BRAKE LINE JUST FAILED. I WAS TRAVELING ON A LOCAL ROAD IN A STRAIGHT LINE APPROX 30-35 MPH WHEN THE ACCIDENT OCCURRED.