Exiting the freeway, a guy rear-ended us at fairly low speed, enough to dislodge and scratch my fender a bit but no injuries or major damage. I pulled over and he sped ahead to the light, got stuck at the red, and pulled into a Costco parking lot to evade me, I think. He saw we were following and he stopped. I got out and started taking pictures of the back of my car. He approached and was immediately combative about whether my car had sustained any damage. We argued back and forth about that for a minute then he went to his car and began bending up his license plate to obscure it from my picture, I think. Eventually he ripped off the plate completely, tossed it to the side of the road, cussed at me some more, then left the scene. After he left I retrieved the plate, went home, and called the state patrol. The trooper advised me that I should have called at the scene, but heat of the moment I just wanted to get home first. My legitimate biggest concern is just that this dude is out there and super irresponsible, and don't want someone else to get hurt. My car is hardly damaged, but I worry more that this guy will have my contact information and address, if they find him at all. What was his game tossing the plate? What would you have done?