Fallout 3 rescuing slaves?

I've already finished the quest for fallout 3 where you have to rescue little kid slaves from paradise falls, and I've also done the one where you have to capture some. I recently decided that I would like to rescue the slaves that recently captured through strictly business, but their cage requires a key. I tried killing all of the slavers, none of them had a key. How do you rescue them? Thanks :)