Hi everyone.
I was just one turn away from taking my family to a kiddie attraction, and wham, there is a loud thud, we get thrown around a bit, and all the kids are crying. I'm thinking what the hell just happened as I look in front and to the sides. Of course when I look back I see what's in the first of the below pictures

-- we were rear-ended!
Almost immediately [and surreally] a BMW Assist agent was talking to us [through the speakers] making sure everyone was OK. They did an excellent job in getting all the necessary authorities and emergency crews to the accident. They happily stayed with us until I told them it was OK to disconnect. Unfortunately, I can relay that BMW Assist works better than I expected, and can be extremely valuable in certain accident scenarios -- especially when young kids [who can't make phone calls] are passengers.
We are mostly OK given the impact; however the car took a bit of a beating. I'm posting to share our experience with BMW Assist, and get advice on what to do with the car.
As far as the car goes, it's definitely injured. I've attached pictures of the damage. The entire back bumper is bust, and the impact managed to deform the area above the right rear tire well. The engine also cutoff on impact and will not start. Could my engine and drive train have been damaged in this type of accident? Are there any other non-obvious components of the car that could have been damaged as well?
It's currently sitting at the towing company's lot while I figure out where to send it. Should it visit a BMW service department or a body shop first? Can anyone recommend either in the San Francisco Bay Area?
Any advice would be greatly appreciated. Thanks.
One last thing -- when all is done, how do I know the car was put back together OK?