Yes, Target (or if attached to a mall, they will have cameras too) have pretty good cameras trained on their parking lots, but the tapes are not stored unless requested usually. Call the store, and the mall, if one, asap to ask that they at least preserve it, even if they don't immediately agree to hand it over. It would be very helpful if they caught the whole scene, including the fake punch, on tape! (They might be reluctant to hand it over to you, but they can at least preserve it until a determination is made. If they do have the scene on tape, you can then safely call the police and they can officially request the tapes.)
It is also possible that someone passing by reported the scene to security, even if they didn't interfere themselves. So you might get an incident report as well.
Sending thoughts of kittens and puppies and butterflies and everything nice your way for you and your kids to crowd these horrible scenes out of your mind.
Take care. Be safe.