Accelerator Pedal problems of the 2004 Subaru Forester

Pulling into parking space. Had foot on brake. Approximate speed of car 10 mph. Car accelerated on its own with my foot on brake. Looked down saw that gas pedal was to floor. Car accelerated into brick building. As quickly as it accelerated it stopped. Was able to reverse car into parking space. Hole in building damaging electricity for building. Entire building without electricity for entire day. Building has a 5' x 5' hole in wall and cracks doing up and down and around corner of building. Car was towed to repair shop since Subaru(forester 2004) does not do repairs. Car was inspected by mechanic who said he could see no visible reason why gas pedal stuck. Frame of car in tack, estimated damage $3600. Car will be repaired and shipped to Subaru for inspection prior to repossession of car. Airbag did not engage during accident. Prior to accident, approximately 2 months ago a similar incident happened. I came to a stop at an intersection, stepped on brake and car accelerated. It took both feet on the brake to stop the car. I thought perhaps it was winter and I slid on ice, or perhaps it was just a freak accident. Didn't think much of it until the second occurance.