Most rats are good climbers. Roof rats in particular are very good and it's most likely this is what you've got since they love attics. The best thing to do right now would be to start trapping them out as explained in our roof rat control article.  Just don't start cleaning the area until you've got them removed and know for sure there isn't any still up there! This way you'll be able to keep them where they've been and in the end, be able to get control that much faster. If you disturb the area, you might end up moving them to some other location in the home that won't be so easy to access. I suggest you review our online article for more details…