What do i feed baby finches?

There was a storm a couple of hours ago and we found a nest far away from trees w/ some baby finches in them. They look like they are only a few days old, and we have them in an incubator. I'm not really sure as to what we should feed them. If anyone knows what i should mush or anything like that, please feel free to share. I don't think that they're big enough to eat seeds yet, and i know earthworms would be terrible for them, so any fruits, or anything that i can mush would be good. We have cat food but i don't know if that would be good. Any and all appropriate answers are appreciated! Thank you for helping.