Restrict your dog's face to face meeting with other dogs unless the other dog is really calm and stable. I wouldn't reattempt a face to face one until those people have calmed their dog down and you make a judgement for yourself if it's "really friendly". They shouldn't have let go. That was dumb.
Mine used to bark her face off but I'd stand a few feet away from the dog and give a correction every time she started running her mouth and it ended really quickly. She only gets to greet if hackles are down and she's making zero sounds.