The red fox in the foreground was hunting mice and other rodents in the snow, and did not notice the coyotes approaching it. Like wolves will kill coyotes, coyotes will kill foxes.
The coyotes became distracted by their own rodent hunting when they reached the area where the fox had been hunting, and the fox was able to evade them. This fox is a color variation on typical foxes and is referred to as a "black morph."
This is the typical color of the red fox. We had four days of "three dog days" in Yellowstone during which we saw wolves, coyotes and foxes.