Today I had a Radroach Infestation incident in my power plant, there were six dwellers in there at full health, most of them armed. They all died. I moved all the dwellers from my water treatment plant and restaurant, most of them were armed, they all died. There was only a single Radroach remaining but it can't be killed and it seems to do a lot of damage. At this point I can't continue playing because I can't kill the Radroach to end the incident and Radroaches now infest the entire vault and I'll probably have to start over.
This is a game-breaking bug, I hope it can be fixed soon.