I have a stupid question about Auschwitz

Hiii steamians this is probably going to be a really stupid question and I feel like I should know this since I'm currently in the process of converting to Judaism.

However, I recently saw a picture of prisoners at Auschwitz and within the line of people there were some Catholic nuns in full habit. Why were they there?

Were they being held in concentration/death camps as well? Or did they somehow take part in the atrocities committed during the Holocaust?

Remember me in your prayers thanks.