[Buster Bailey]

I was just wondering what the best thing to do is if my 2 yorkies & I are approached by a mean dog on our walk. We were walking yesterday, and I'm sure I did everything wrong but I went with my gut reaction. A very large black dog of some kind came snarling around the corner of a backyard and I thought it was going to eat Buster & Bailey! I kind-of shreaked & yanked Buster & Bailey by their harnesses/leashes up into my arms & continued walking. I thought about standing up to the dog, but if I did that I think it would have bitten me or my yorkies. Buster & Bailey were not calm to say the least, and I was petrified that the dog was going to bite them or me. The dog's owners were outside & yelling at it, and the dog stopped a couple of feet from me, turned around, then came back towards me a few different times...it did not listen very well to its owners. I tend to take various routes around town so I don't get bored & neither do the pups. I shiver to think what would happen if I'm approached by a dog like that and its owners are not around. I think that had I not picked my furkids, that dog would have bitten them & not let go. Any suggestions on what to do if you're approached by a mean dog on a walk with your dog(s)?