Illinois Congressman Jesse Jackson Jr., whose whereabouts haven't been disclosed since he mysteriously took a medical leave several weeks ago, is being treated for depression at the Mayo Clinic in Rochester, Minn., according to a statement Friday from the hospital.

Jackson is undergoing an extensive inpatient evaluation for depression and for gastrointestinal issues, according to the statement, which also provided the first details about his medical condition. But it provided no details about where the congressman, the son of civil rights leader Jesse Jackson, had previously been staying.

"Further information will be released as Congressman Jackson's evaluation proceeds," the statement said, adding that he and his family were "grateful for the outpouring of support and prayers that have been received throughout his care."

Jackson went on leave June 10, though his office didn't disclose it until weeks later and has been mum on details ever since.