If the dogs normally roam around call the animal control. the owner will have to pay to get them back. if the dogs aren't up to date on shots they will give them to the dog and charge the owner. i really hate to do that but if you've warned them i'd say go for it. also better check your law on shooting a dog. around here it's the same as a person you have to feel like you are in immediate danger. you can't just shoot one that is in your yard for something it has done in the past.
however that being said the first time it pinned my kids would have been the end of worrying about that dog for me. i would fully expect the same if my dog went to someones house and was aggressive. i don't believe in having a dog that will bite. we have a dog. his job is to let us know if someone is around our house. if he bit anyone he would not stay. you can't see neighbors from my house so they would not know what happened to their dog it would just disappear. if you live in town i'm sure it will be hard to conceal what you do.
for people in town it's probably better to call animal control. they probably won't pay to get the dog back and it can go to a good loving home.