Also some recent happening from outskirts of Moscow. Some people had some criminal conflict that resulted in shooting with hunting rifles. Reasons are unknown, although some of them already found by police.
Of course at least half of them are Caucasians (in local terms).

Compared to USA, it is very rare to see any rifle shooting in Russia because civilian arms market is pretty strict and self-defense is almost prohibited. This doesn't stop that type of people though.