I parked my 2017 Cadillac in a parking spot put the car in park shut it off and put the brake on went in side the pharmacyand my daughter was in the passenger seat with the windows downwind the car went Forward and hit a pole then rolled back and wrecked in the two cars with the car shut off in park a man tryed to stop it and the brake pedal was hard as a rock and the car was still in park . I got in to move the car and it was still in park .. I had the keys in my pocket in side the pharmacy..