When I was training with my first working dog trainer, I got to see how they did employ I don't remember now what they are called, but they look like a rolling pin without the pointey handles. A Rottie and a Anatolian Shepherd went at each other! Not a pretty sight. That wooden thing was used to break the hold of the Rotties jaw. Oh and BTW both dogs were neutered, and fully adult and in an advance obedience class
And Jillie there ended up three guys keeping those two apart, and were big burly men.
I certainly did not see what started it off, but I followed my training and got the hell away from the area with Magic!