Did multiple brake lines fail at the same time? Usually there are two different brake circuits, each controlling a front wheel and the opposite rear wheel (front left, rear right). So if one line goes out, only 2 wheels lose braking. The fact that you started rolling seems to say that either multiple lines went out or something else went out. Maybe the master cylinder or the actual pedal. I presume that when you pulled over, you saw brake fluid on the wheels and/or ruptured lines. Is this the case? If so, which corners were ruptured? Or am I totally off base and the X only has one brake circuit?