Rats and Mice tend to live somewhere near their food sources, although they will also seek out safe places to live/sleep/breed. But they don't like to travel far between food sources and home, so if you keep food away it helps deter them from living there.
Mouse and Rat populations tend to expand to fill an available area until they consume all the resources or are controlled by predators. As such, the idea of killing all the mice in a building before you have closed off their access points only serves to create a "vacuum" whereby more mice will be drawn in (from the available population outside). And keeping Mice and Rats out of a large building can be completely problematic.
Since you can't really make a vacant building any less inviting to a Rat/Mouse that wants a home, about the only thing you can do is to make sure there is no food around (and that especially includes outside the building, like dumpsters and stuff).