IT WAS A SCARY SITUATION ON 08/08/2018, MY '07 TOYOTA PRIUS 2 FAILED TO STOP WHEN I APPLIED THE BRAKE TO STOP AND PARK INSTEAD IT ACCELERATED. DRIVING THROUGH THE PARKING LOT OF SEAFOOD CITY IN CERRITOS, CA, LOOKING FOR AN OPEN SPOT, I MAINTAINED PRESSURE ON THE BRAKE PEDAL TO KEEP A SAFE SPEED. APPROACHING AN OPEN SPOT, I CONTINUED TO KEEP PRESSING THE BRAKE WHILE ENTERING THE SPACE. AS I WAS STRAIGHTENING MY STEERING WHEEL AND APPLYING A HARDER BRAKE TO STOP, I FELT THE CAR ACCELERATE FORWARD, CAUSING MY INSTINCTIVE REACTION TO APPLY EVEN MORE BRAKING PRESSURE ON THE PEDAL. THE CAR CONTINUED FORWARD UNCONTROLLABLY, JUMPING THE CURB OF AN ISLAND, HITTING AND KNOCKING OVER A PALM TREE (APPROXIMATELY 15' TALL) ONTO A PARKED VEHICLE (CAR #2) TO THE IMMEDIATE LEFT OF THE VEHICLE DIRECTLY IN FRONT OF ME (CAR #1). MY VEHICLE DROVE UP THE TREE AND CAME TO A SHORT REST ON TOP OF THE HOOD OF CAR #1, WHERE MY FOOT WAS ON THE BRAKE THE WHOLE TIME. IMMEDIATELY AFTER STOPPING, AND REALIZING THAT I WAS STILL APPLYING A HARD BRAKE, TRYING TO GAIN CONTROL OF MY VEHICLE, THE VEHICLE BEGAN ROLLING BACKWARDS DOWN THE TREE AND OFF OF THE HOOD OF CAR #1. THE CAR DIDN'T STOP ROLLING BACKWARD DESPITE MY FOOT WAS PRESSING HARD ON THE BRAKE. IT WAS THE COUSIN OF THE OWNER OF CAR #2 WHO REACHED AND PRESSED THE STOP WHERE THAT'S THE ONLY TIME MY CAR STOPPED ROLLING AND CAME TO A COMPLETE STOP. IT WAS THE WORST FEELING AS I WAS NOT IN CONTROL OF THE CAR AS THE BRAKE DIDN'T WORK. I WAS SO SHAKEN, ME