No, not saying that only pits attack. My understanding is that there is considerable confusion as to the true identity of a "breed" known as pit bull, and that it is a variety of dog mixes that are, correctly or not, commonly called "pit bulls." Then there are Rottweilser. And in the days when Dobermans (I think those dogs are cool) and German Shepherds were in vogue, those were the dangerous one. The point is that certain kinds of dogs, when they attack, can cause a hell of a lot more damage than most other dogs who are just as aggressive. Just because a dog is aggressive doesn't mean it has the same deadly potential as another aggressive dog.
You are correct that it can be hard to identify the breed. Click on my screen name and play Pick the Pitbull.