I thought she died when I heard the "thump"

The short drive leading down to my cmplex from the main road runs at a slightly steep angle, enough so that at this time of year, there always seems to be a car spinning its tires just inches from the cleared blacktop of the main road. Such was the case as I arrived home Friday afternoon. I passed a woman with spinning tires, parked my own car then thought to myself 'she is soo close, I could give her a quick push and she will be to the street'.
My charitable side should have died with that thought....after several attempts at pushing her, she was still getting nowhere, she rolled down her window and after a moments conversation I realized she did not speak much English. We attempted the feat several more times. Reversing the car and starting from a gentler slope. Finally, within feet of the main road, she communicated that I should open the passenger's side door and push, I placed myself, unsure of her idea. Then she opened her door and stepped out, bracing herself against the driver's side door. I watched in horror as she put the car in neutral. NOT a good idea.
I desperately tried to tell her to put it back in drive, but it was too late, the car had begun to slide backwards, its open doors pushing us down the hill with us. I threw myself into the door, knowing even as I did so we stood no chance against the car's momentum. The sliding became faster, and we were losing control. I yelled through the car at her.
"Emergency brake! pull the emergency brake!" She was struggleing more than I was, my eyes frantically searched the car for a brake. The car was going faster down the hill, pushing us backwards as it did. Faster, Faster. Fear now, panic. Faster. I heard her scream and through the car I saw her fall. Then I heard the "thump", and the car ran over a bump, then seconds later smashed into a fence. Silence.
I ran around the car to see how bad the damage (to the woman) was. Thankfully the bump the car hit was only a pile of snow, the car hit the fence moments before it would have run her over. I was relieved.
The back tail light was smashed and part of the bumper was damaged, but the woman, though scared, was unhurt. I eventually managed to drive the car myself up to the street while she called her husband for help. It was a very scary experience. I thought she died when I heard the "thump".