WHILE BACKING OUT OF DRIVEWAY, WITH FOOT ON BRAKE PEDAL, I SHIFTED THE 2003 CAMRY FROM PARK INTO REVERSE. THE CAR IMMEDIATELY ACCELERATED BACKWARD AT HIGH SPEED OUT OF DRIVEWAY, CROSSED THE ROAD, AND CRASHED INTO A TREE. 3 PEOPLE IN CAR, NO INJURIES. SO FAR, ESTIMATED BODY DAMAGE IS ABOUT $8000, BUT UNDERCARRIAGE HAS YET TO BE INSPECTED. REASON FOR SUDDEN ACCELERATION IS UNKNOWN.AK