Car parked in park and ride – right side scrapped

I parked my car in a park and ride last night and went to get my car this morning. The right rear is all damaged like someone drove into it. I have no idea how it could have happened and there’s no note. I filed with Insurance because I have collision but I’m worried it won’t be covered because of the extent of damages?? This is my first time dealing with something this bad. My car was hit in a parking lot and the gas cover was dented. Insurance covered that no questions asked but this is worse. I took pictures. Should I file a report with police? My car is driving condition and I drove it home.