Sara, I called the second shelter that Aly suggested. She said if you go to a petstore (Petco, Petsmart, any pet store) they should have Kitten formula and the one you buy depends on the age of the kittens. She gave me some milestones to help tell the age, but it sounds like these are younger than what she gave me.

Eyes open about 10 days
3 weeks they start standing and wobbling around
by 6 weeks their eyes start turning to their permanent color

She said if the kittens are still there, the mother might still be coming back and feeding them even if she moved the others. One way you can tell if she's not coming back is if they are very vocal. If they are crying their little heads off, they are very hungry and you need to help. If they're not crying, feel them - but don't handle them too much - to see if they are cold. They can't regulate their own body heat so they can't be cold, so if they are they need to be brought in and warmed up.

The lady was very helpful and nice and said to call back if you/we need more advice. Hope this helps!