I was wondering if someone could help me out... I am at a constrution..

I figured this out quickly enough, but it still rankles me because when you start the generator off to your right, the light should kill the slayers. It worked earlier in the game anyway.

In any case, what you need to do is use the rock held by the crane to push another rock over the pit the slayers spawn from It doesn't seem to matter how quickly you do it, the guards die inexplicably as soon as it is covered regardless of how hard you try to save them so don't let it frustrate you when they keel over even after you 'save' them.

Also, the rock can be positioned as a stepping stone between the ledges so you can steal the shotgun ammo left directly across the way from where you entered.