Another bomb threat shakes up a school in Muhlenberg County. This is the fourth call in the past few weeks. Today's call was made to the North Middle School in Greenville. A bomb threat was also called into the South campus Monday. These two calls follow two others at the county's two high school campuses. All of the threats have been hoaxes. Kentucky State Police detectives arrested two people for the calls to the high schools. They are still looking for the people responsible for Monday's and today's calls.