vellad -- Agh darn. That's not good.
Personally, I would put them under a warm lamp or on heating pad (on low) and I'd quickly get set up with handfeeding and a brooder.
There are a couple sticky threads on making a brooder and handfeeding.
I would actually start with some warm (104-106 degrees) unflavored pedialyte or homemade rehydration solution (there's a sticky for this too), as they're likely dehydrated. (Look at the neck area; if it has a dry wrinkly look or if they have a bright/dark red coloration.)
I'd do 1-2 feedings of that, then transition to formula.
If you don't have a commercial handfeeding formula on-hand, you can make your own. I have a recipe here, with items that most people will have on-hand:
http://wp.me/p4JWrl-ar
Then, I'd start feeding them.
But I'd also check that the nest is sufficiently deep. If it's too stuffed with nesting, they may have rolled out (i've had that problem.)
Was there a fourth one still in the nest? If so, I'd also put down some paper towels, a few layers thick, so you can clearly see if the other one is tossed (and it will soften the landing.)
It's possible that if the parents aren't feeling well, they tossed due to that. I've had that happen. I had a hen come down with twirling right when the babies hatched.
