Something Thumping

Empty house in decent shape. Wasn't much to see but something was banging away upstairs about 10 mins into my first visit. Loud enough to get me up and out in a hurry. Not the usual scratching and pattering feet of a coon or the crazy spasms of a frightened feline. This was almost the sounds of humans stomping towards the stairs above me. Not shooting the upstairs was driving me nuts so i went back to finish what i had started. This time however, the house was silent. Probably the closest I've felt like something paranormal was happening around me. The property was cleared a year or so after my visit and is now a worked field.