I've been involved in this before and everyone is right, call your insurance company ASAP. Deal with them and they will deal with Geico. Even though you might be in a no-fault state, the insurance companies will determine the percentage at fault between themselves. I can't see how you would be assigned any fault as you were stopped and were rear ended.
That's how I got plowed a few years ago and my rates never changed. The assigned it as 0% my fault and never changed my rates.