I live kind of close to downtown in a really nice neighbourhood, but the downtown street people comb the area for blocks and blocks on the recycling nights looking in bins for bottles they can take back for money. I'm pretty sure they are the ones who took them to carry their bottles around. There were these great big biciycle tires on my triple stroller. They might have wanted those for a bike.
My play area is visible down the driveway to our street so the only other option was that a family with a child stole them. Either way, my trust in human beings has been dashed yet again.