Few pilots, relative to the total population of pilots, will ever be where that Black Hawk and CRJ where. On a few occasions I have been there both unadded and added with NVGs. It is a terribly tight and unforgiving place with lots of lights and ground objects to distract attention of the heli pilots. The fact there was two DC Guard pilots and a third crew member, most likely all three using NVGs and very familiar with the area and they ran into a CRJ tells me maybe the CRJ hit them from the rear. The CRJ pilots never really having much of a chance to see the Hawk in all the ground lights. Condolences to all. Terrible accident.