Specifically, the owners of the improperly supervised kid. From the I, Anonymous forum:

I saw it all. You guys weren't paying attention to your kid. She ran up to a dog five times her size and tried to grab the dog's face. She scared the dog and it bumped her with its nose, and your kid cut her lip with her own teeth. She starts crying and you two start freaking out at the owner. First: You're at a festival with thousands of people—you should hold your kids hand, or at least be watching her, so you don't lose her. Second: Not all dogs are raised with kids, and not all kids are raised with dogs. You need to teach your daughter to ask to pet a strange dog, not run up and grab its face. Third: the dog did NOT bite your kid. It pushed her with his face because she SCARED it (being bit involves the dog opening its mouth.) Your kid bit herself. You guys need to learn to control your child. If you can't keep her under control, get a damn leash or a babysitter. The dog was on a leash and this wouldn't have happened if you were paying any attention to your kid. This was all your damn fault. I feel sorry for your daughter; she's being raised by neglectful assholes.