How scary! I had the exact same thing happen to me yesterday! I let the dogs out into the backyard for the third time of the day. Nobody came when I called them in. I looked and the gate was open and there weren't any dogs. I went to the front of my house and saw Iker a few houses down. I ran towards my door and he followed me into the house. Then I grabbed a leash and collar to look for Treasure, who was absent. I called her a few times, and somebody from the nearby trail replied that he had her. A wonderful man with two little dogs heard me calling her. He called her and she came to him, so he grabbed her collar.
Very scary! I am so glad that your story has a happy ending.