I really like the background and the colors you've chosen. The people look, well, not quite ideal, though. The gun looks like a spike at the end of the shooter's arm.
Honestly I think it could be redone as a pure landscape and it'd be really nice, but I am the biggest sucker for landscapes, so of course I'd say that.
It kinda looks as though the shooter only has one arm and the person fleeing and the shooter are perfectly perpendicular to the 'camera view'. But still very nice! Probably much better than anything I could draw.
I agree, I think the characters aren't as good as the environment. Maybe I'll remove the characters and do something else with the background for a new piece.