I would bet the gun in the picture is either a toy or or some home modified experiment. The gun holders right hand does not have a natural hold on a pistol grip - maybe there is some kind of sawed off stock at best.
The fore grip looks like it has vent slots cut in it, but the barrel(s) look like an over and under shotgun. I also don't see any sign of an action or ejection port. Put it all together and I guess it's a toy, but the kind of toy that could get someone killed. I would shoot if I saw it pointed at me. Then I would figure out what "it" was.