2016 Lexus NX200T

I ENTER THE VEHICLE, APPLY MY FOOT TO THE BRAKE TO START THE VEHICLE, ENGAGING THE REAR END LIGHTS. I KEEP MY FOOT APPLIED TO THE BRAKES, NOT SHIFTING THE CAR OUT OF PARK, WHILE I RESEARCHED DIRECTIONS TO MY DESTINATION. MY VEHICLE REMAINED STATIONARY I REALIZED I HAD FORGOTTEN SOMETHING, SO DISENGAGE THE BREAKS AND SHUT THE VEHICLE OFF. I BEGIN TO EXIT AND AS MY SECOND LEG IS HALF WAY OUT, THE VEHICLE BEGINS TO ROLL BACKWARDS. I WAS ALMOST PINNED BY A STREET SIGN, AND AFTER AN UNSUCCESSFUL ATTEMPT TO GET IN AND GAIN CONTROL, MY NEIGHBOR HOLLERED FOR ME TO LET IT GO, AS THE BACK END OF THE VEHICLE FORCED ME TO BE PUSHED TO THE GROUND. IT PROCEEDS DOWN THE HILL MAKING CONTACT W FOUR VEHICLES.