Very sad. Every potential dog owner should remember one thing above all: no matter how large or small the dog there is wolf DNA lurking in every cell. In this case the wolf emerged when the security of restraint by the owner - alpha male to the rott - let it down and it panicked. There were all sorts of better ways the onlookers could have handled the situation, but they weren't to know them. A tragedy for owner and dog both.
Two of our three dogs, our Siberian huskie and our akita are ancient breeds and have more wolf in them than most, with the akita carrying over 99 percent wolf DNA. They are both well behaved creatures, and the akita has snapped exactly once in his life, at a vet who accidentally gouged his eye with her thumb. Nevertheless we regularly stress to the kids that no dog is entirely safe, especially to our son as the akita has become his shadow.
By the way, it's our bearded collie who exhibits the nearest we have to bad behaviour. He prefers the ladies of the house, and I have a dominance battle with the bugger every time I return from working away from home