I parked my car in my driveway and accidentally left the gear in park when I turned off the engine with the push button. This is the first time I had driven this car so I didn't know what to do for the warning beep. I exited the car and took the key fob with me. My daughter exited the car just after me and when she closed the car door the pressure was enough to start the car rolling backwards. The vehicle rolled down our driveway which has a steep slope, across the street, over our neighbor's yard and crashed against their house. We are lucky that no pedestrians or other vehicles were involved. There is significant structural damage to the neighbor's house. A police report was filed. I believe this is a significant safety hazard that a driver could turn off the engine and leave with the key fob while the car is in drive and there is no braking mechanism to prevent the car from rolling! In addition, the quiet warning beep should be more pronounced such as the horn honking or something more extreme to get the attention of the distracted driver.