I just had an encounter with some goblin ambushers in front of my fort. Most were caught by cage traps, and I sent my troops out to finish the rest. However, somehow, two dwarves were captured, and now they're sitting in their "dwarf cages" in animal storage.
How the heck do I get them out? How did they get in there in the first place - I thought my dwarves were immune to their own traps.