Fili, Kili, Dwalin and Bilbo were forced to jump from the tree they had been sitting in into the next one across when the wargs pulled that one up by the roots and it started to collapse. Before long, all thirteen dwarves, plus the wizard and hobbit, were all squashed into the top branches of one tree, which was starting to fall off the edge of the cliff.

As Ori fell backwards out of the tree, Nori lunged to try and grab him, but fell out himself, crying out. "Mr Gandalf!!"
Gandalf quickly stuck out his staff, which the dwarf could grab on to, and kept a hold of it, with Ori hanging tightly onto Nori's boot. They were safe, for now.