I could be wrong but if it happened at night it wasn't a hawk. How big is your pin? When you say picked clean, that sounds more like a possom or something.
Before you give up, make your pen as strong as possible, this will make it less likely to loose birds.
No it was definitely this morning. I let them out at 7:30am and they were fine. Good news though I found the other two! They were hiding under the coop. Unfortunately it was my sons favorite that died, but he took it in stride and just named the other Buff Fatty. I told him she missed Lisa so much that we gave her back so she wouldn't be sad. I know I should let him face reality, but he is still sad about Snake the chick that didn't grow much and died in his cage. The remaining two chicks are all locked up in the smaller coop.