Try to catch them in live animal traps, give them 1 chance. Only 1. Its not the dogs fault, its the owners. Dont take your frustrations out on the dogs, they dont know what they are doing is wrong. Take them back to the owner if possible and ask that they keep an eye on the dog. If it happens again, take them off to a animal shelter/pound and mail the collar back to the owner and tell them where they can find their dog.