Too bad your kitties only alerted you to the intruder, and not taken care of it. Fortunately, we don't have mice in our apt., however, when we lived in NH we would get "visitors" occasionally. TJ (the cat) would take care of the intruder, after putting it into the tub and "killing" it with vertigo from being chased around the tub. I've had cats that were good mousers, however the method of catching and putting the mouse into the tub was a new one to me. Aren't cats wonderful companions, and at times great entertainment?