They'll be fine on any chicken feed. I've fed chicks on layer, and fed layers on chick starter (with free-choice oyster shell). The only difference is normally that layer has slightly less protein, and significantly more calcium--otherwise the formulas are generally almost identical. Some people say the excess calcium in layer feed isn't really good for growing chickens, but I've never had problems with it myself--regardless though, it definitely won't hurt them in the short term at least until you can get more chick feed if it's a concern to you.
If it's in a pelleted form though, you might want to put a bit in your food processor or blender to break it up into crumbles for them, as pellets can be awkward for small chicks to swallow. Alternatively, you could moisten pellets with water and feed as a mash (oatmeal-like consistency is good). They'll probably like that even better.
