My freezer is buzzing- loudly!

Question

Yesterday I noticed my freezer buzzing, but it wasn't loud and I thought I'd wait and see if it would stop.  I also moved some things around thinking that maybe something was just vibrating against the back part of the freezer.  This morning it sounds like my freezer is going to take off, it's so loud!  I removed everything from the freezer.  What do you suggest?