Wow, scary stuff! I'm glad you ended up finding her safe and sound!
Something similar happened to me when DD was about 2. I was doing something, can't remember what but it was likely laundry

, in the middle of the afternoon. DS, 3 at the time, was playing in the back yard (fenced) and DD was in the family room watching a video on tv. Suddenly, I realized that DD wasn't laughing or singing along with the movie like usual, so I ran to check on her. And she's not in front of the tv. I call for her and get no answer. I run outside and call for her. DS hasn't seen her. I yelled for her again, and the neighbour pops his head over the fence wondering what's wrong. I must have sounded terrified. He helped organize a search posse of all the neighbourhood parents and we start combing the neighbourhood. He asked me a couple of times, are you sure she's not in the house. Yep. Positive, I had looked for her quickly and called for her. Well, by this time it's 10 - 15 minutes after I noticed her missing and I'm really nervous. We lived on a cul de sac just off a couple of very busy streets with a small walkway connecting some other streets. He insisted that I go back inside to check for her one more time before we called the cops and start looking past the walkway. So I went back in and called for her one more time.... and she answered! She had been hiding on me and she thought it was funny. NOT! I was so relieved and felt like such a moron when I told the neighbours they could quit looking for her... But at the same time, it was good to know that everybody would pull together for us.