That has happened to me a couple of times when I walk Beenie and Frankie.
Both times, the dogs that were running toward us stopped a few feet away after I started yelling NO really loudly and stimping my feet.
When They were pups, I could pick them up but now, at a combined wieght of 55 lbs, that's not possible.

I wanted to add that once, when Frankie was a pup, he was in the back yard and started running toward the side yard barking. He was running toward the meter reader. She quickly opened a small umbrella before Frankie reached her and scared him! That was a genious idea and you may want to do that even though I'm not sure how fast you could open an umbrella while walking 3 doggies! I know I probably couldn't with the two of them... but just an idea.