Short glace based on some old data.
Sakhalin (majority Russian) 126 dead, Karachaevo (non-Russian) 43, Adygeya (non-Russian) 65, Kostroma (Russian) 132, Karelia (Russian) 76. All of them are approximately 0.5 million. So, out of this:
-Ethnically Russians have the most losses.
-North Caucasus have almost twice as little losses.