"They fell upon the fox and tore her to pieces ..." (line 10) 'They' in the sentence refers to?

Read the text then answer questions 1-10.

    One day, a cat and a fox were having a conversation. The fox, who was a conceited creature, boasted about how clever she was. "Why, I know at least a hundred tricks to get away from our mutual enemies, the dogs," she said.

    "I know only one trick to get away from dogs," said the cat. "You should teach me some of yours!" "Well, maybe someday, when I have the time, I may teach you a few of the simpler ones," replied the fox airily. Jus then, they heard the barking of a pack of dogs in the distance. The barking grew louder and louder. The dogs were coming in their direction! At once, the cat ran to the nearest tree and climbed into its branches, well out of reach of any dog. "This is the trick I told you about, the only one I know," said the cat. "Which one of you hundred tricks are you going to use?" The fox sat silently under the tree, wondering which trick she should use. Before she could make up her mind, the dogs arrived. They fell upon the fox and tore her to pieces.

"They fell upon the fox and tore her to pieces ..." (line 10)

'They' in the sentence refers to?