Good Hobbit Morning chapter 4 "Over Hill and Under Hill"

As Gandalf and the Dwarves slept, Bilbo was troubled by nasty dreams; to his horror, upon waking from one nightmare, part of his dream became real. A wide crack had opened at the back of the cave and he saw the ponies disappearing into it. Bilbo let out a loud yell and suddenly the cave swarmed with goblins who grabbed them all and carried them through the crack. However, upon Bilbo's shriek, Gandalf had awoken in time to avoid being taken and killed several Goblins in "a terrific flash like lightning".