Forclosed House w/Previous Own still Occupying

I was looking at a REO House on auction.com but the previous owner is still living in it. How horrible is the eviction process in Massachusetts with this situation? Is it the same process as a rental eviction? Or since this is a foreclosure are they illegally squatting and can be legally removed right away?

I understand I should be asking a lawyer but wanted to hear of my fellow BPs opinion and experience.