Members from Mid-State Composite Squadron 239 were activated on an Air Force authorized mission last week.  The Air Force Rescue Coordination Center reported that an ELT was being heard by overflying aircraft in the vicinity of Mid-State Airport.  Members of Squadron 239 were activated on the search.  Despite spending hours on the search and traveling over 100 miles, they were unable to detect the ELT.  It is presumed that the owner of the device deactivated it after being accidentally turned on.  No overdue or missing aircraft were associated with the search.  Other Group 5 assets including ground teams and assets were involved in the search.