Body problems of the 2003 GMC Sierra

I was parked on a sloped driveway (about 10 - 15 degrees). I started the engine, stepped on the brake pedal and took the car out of park into drive. Brake pedal was normal. I started to roll forward and when I pushed the brake pedal the car did not slow. I slammed the brake pedal and it went all the way to the floor. At this point I went off the end of the driveway onto a 45 degree downward sloped lawn; then into a wooded area at the top of a ravine. I slammed into a tree. The car was judged a total loss by my insurance company. I did not get a brake warning light. The airbags did not deploy. The car was serviced at a union park GMC (wilmington, DE) two days prior. Including brake inspection. Cause of brake failure was determined to be ruptured brake line. Both front and rear brakes were failed.