Oh thanks everyone. My poor son feels terrible, and he saw me cry, which rarely happens. I just felt so awful and it happened so quickly. I supervise them so carefully but I wasn't next to him as he started to fall over.
His dad picked up a new (old) beater truck with an extended cab just now, so that made him feel better.
I know these chicks are fragile, and pray we can get the rest of them to adulthood.
Bless my dh (who didn't want any chickens to begin with, or any of the animals we have for that matter). When he came home and the kids told him and he saw my face, he said "Call the folks you got them from and get some more." Now that was sweet.
Thank you again. This is such a great place. If I told this story to most of the folks I know, they would make some joke about cooking them up or something.