River succeeded in grasping his shoulders, but the man was elusive, and soon they were rolling around exchanging feeble poorly timed blows. With a grunt, River thrust her fist into the back of the attacker's head, knocking him out cold. He slumped into the dirt, and she got up, releasing her pent up breath. There was a crashing in the shrubbery, obviously another human. Will this one be as disagreeable as the last? Preparing for the worst, she began looking for escape paths. 

Perched in the tree, River could get a good view of the source of the noise. The crashing came from a female, armed with another one of the deadly weapons she doesn't understand. Maybe she's affiliated with her attacker, in which the best thing to do would be to hide and hope for the best.