I'd question what the guy was doing to cause the dog to get so mad as to get out of the gate in the first place. Sounds more likely the dog was doing it's duty in guarding the property.
This was my first speculation, hence my comment above about not judging the vic since I don't have more info.
You don't know that dogs bounce off the fence trying to get at whoever's on the other side? They're always trying to burrow out, like this one did. Some are chained and all they do is try to break the chain.
" Sounds more likely the dog was doing it's duty in guarding the property."
Then the dog would be inside the house. Else the entire house must be securely fenced and marked. This dog was outside it's fence.