Tis' the season for mice. Its the time where they look for shelter indoors! Since we adopted our cat (he's indoor/ outdoor) and replaced our basement door with something that is sealed, no mice sightings. Every once in a while they creep through, but that is easy to fix with traps. When the cat is outdoors he does keep pests at bay. Keep setting traps until there is no more activity. It's slow, but it works. In the mean time, hopefully you've checked for entry ways around the area and seal them up. Good Luck!