Fuzzy animals under shed floorboard?

My dad has an old shed in our backyard, and we need more parking space, so we were going to tear it down, but the other day, I saw a fuzzy animal crawl under the floorboard of the shed ( there's a gap in between 2 sections of the floor, and there's a whole in the top section, so its kind of a rectangular prism with a whole in it.) The creature was at least 1 foot long and it had small beady eyes like a beaver, it was the color of a rabbit but it's ears were small and it had a long, flat tail. I think that there might be more living under our floorboard, so i want to know how to get them out before my dad knocks the shed so they don't get hurt, and I would also like to know if anyone knows what kind of animal this is.