[quote=Freeshooter92]
Calling the Grey knights is basically just telling them to kill everything! It would be cheaper, faster, and more entertaining to just call down an exterminatus, But there are CIVIES down here! We can't just nuke 'em from orbit!
[/quote]
...When has that ever stopped the Imperium when it comes to chaos? 
No, seriously. Pretty sure they don't care. Most of the time. If you really wanna save the innocents, there's only one thing left to do...
[img=http://media.desura.com/images/groups/1/3/2055/SalamandersAstartesFlamer.JPG]
Call in da orkiest of marines.