What was that?!

Today, Brian, the kids, and I, were on our way home and came to a stop at a stop light.  A few seconds later the car lurched forward with a big bang.  Brian had to slam on the brakes because we were being pushed forward were getting very close to hitting the car in front of us.  We were rear-ended.  It took a few seconds to realize that was what had happened.  That was a first for me, and all of the kids.  (Not sure about Brian...)  We immediately checked with the kids to make sure they were all ok, which they were.  There was a cop at the same intersection, but going perpendicular to us, so we tried to flag him down, but he was oblivious to all of our attempts.  So we pulled on to a side street to assess the damage and talk to the person who hit us.  Luckily no damage to our car, one benefit of having an SUV I guess.  His car was not so lucky. 
Anyway, I'm glad we were all ok.  :/