When I was six (28 years ago) my mom and dad took me and my younger sister to a MLB game, leaving my grandmother to baby sit my youngest sister. When we got back my grandmother told my folks that two guys had come by the house with photography equipment and asked whether a young girl with red curly hair lived there, and that they had spotted her and that she would be a great child model for some advertising work they were doing. When my grandmother said she wasn't home they said they would come back another time.
My grandmother and mom didn't think much about it, but my dad said "Something's not right here" and called the police. 15 minutes later several FBI agents showed up and began conducting interviews with my grandmother and my parents while I ran around and showed the agents my matchbox police helicopter.
Turns out we had been targeted by a child theft ring; the photographers would take a bunch of photos and wait until the toddler threw a tantrum and the photographers would then ask the mother to go grab a toy to keep the child entertained. While the mother was out of the room, they would grab the child and bolt, leaving everything else behind. The FBI told my folks that my sister had already been sold and would have been out of the country within 24 hours if they got her. We were advised to change preschools and other aspects of our daily routine.
It still gives me the chills to think about what could have happened to her. Needless to say, mom became pretty overprotective; it was a few years before she even trusted us with a babysitter.
Edit: Reddit police are calling BS on my story. That's fine and I don't much care because I don't reddit for karma (view my nearly one year history and posts for confirmation). I will say that certain facts may have been conveyed to me with slight exaggerations (FBI probably did not respond in 15 minutes but it was same day and during daylight hours) but it does not make the essence of the story any less true. We are just fortunate that everything worked out.
TL;DR: Child theft ring targeted my sister.