On XXX, our 2023 Ford Bronco, VIN [XXX], was stopped on an incline. The vehicle was not moving, and the driver exited the vehicle believing it was in Park. The vehicle was actually still in Drive. A passenger remained in the vehicle. While the Bronco was stationary, the passenger pressed the START/STOP button from the passenger seat to turn the vehicle off. Immediately after the vehicle was switched off, it began rolling backward down the incline. The passenger was unable to safely stop the vehicle and attempted to exit the moving Bronco. The open vehicle door struck the passenger in the back of the leg/hip area. The passenger had to throw herself to the ground to avoid being dragged, run over, or more seriously injured. The Bronco went off a significant drop off and crashed into a tree. The passenger narrowly escaped the vehicle before it went over the drop off. After the incident, the vehicle displayed a "Park Aid Fault" warning. Ford's 2023 Bronco Owner's Manual states that a "Transmission Not In Park (P)" audible warning is supposed to sound if the vehicle is switched off before being shifted into Park and also if the driver's door is opened before the vehicle is shifted into Park. [IF TRUE: We do not recall hearing a Transmission Not In Park warning before the rollaway.] I am concerned that the vehicle remained stationary on the incline while still in Drive, creating the appearance that it was secured, but began rolling backward when the START/STOP button was pres