Looks like the griz got some surprise on the bison, judging from the apparent wounds and hair in the flank. Probably got away, but depends on how deep those wounds were.
My first impression when I saw the pix was that the Grizzly had already mauled the bison,and that the bison had gotten away and was on the run. But then the photographer said the bison was burned - which I thought was really strange. How would he know that? Those flesh wounds also look pretty new to me, and look much more like grizzly work than a fire or perhaps a falling into a melting pot through the snow?