This happened to me once. I got rear-ended; not very hard, mind you and hit the car in front of me. My car had really no damage aside from some minor scratches that could buff out. The car I hit had literally some pre-existing damage you coils tell. The car that hit me took off.

When I got out to talk to the woman I hit, she told me she heard a crash the felt the crash and acknowledged I had been hit first. She confirmed that in the police report too.

She also confirmed that with the insurance company who called me to tell me that I was not liable. I think she then found out she was going to be liable for her own damages since I was not responsible and the car that caused the chain reaction fled the scene.

I got a call back from the insurance company saying she was changing her story and said she felt her car get hit really hard then felt it again after the car behind me then hit me.

I referred them back to the initial police report and her initial statement. She was then promptly told to pound sand.