Somewhere, you missed a spot with your workbenches. That's why they spawned inside your base. Had that happen a couple of times. Usually it was Gray dwarfs spawning in, but once it was 3 Fulings and they killed me just as I was going to sleep.

Took me forever to spawn, get equipped and take them out. Musta died 3-4 times before I got lucky. Then I found a 1 meter area that wasn't covered by a workbench... ~(8(I) D'oh!

Next time that happens I'll spawn another of my fully armored characters and have him take care of the nuisances.