I was out there, but left before the fall. I know the belayer and a couple of the people in the group, but not the leader.
From what I've pieced together, it was an over 50' ground fall. Leader was at the anchors, built the anchor and prepared for lower. The belayer began lowering. A few feet into the lower, the leader jumped or bounced off a ledge. This introduced slack into the system and pulled the rope out of the belayer's hand. She was unable to regain control of the rope. The leader impacted the ground with her butt and lower back.
My friend who was still out there is writing an accident report. I'll be sure to link it here when he's finished it.