Joe Jackson has been hospitalized.
A source close to the family confirmed to PEOPLE that things were very serious for the Jackson patriarch, but "he is out of danger now."
According to TMZ, Jackson went in for some tests on Friday, but became weak with a high fever.
Sources say Jackson doctors haven't been able to pinpoint what's causing it the fever and a family insider revealed, "We still have to keep a close watch on him."
Jermaine Jackson told paparazzi, "Listen, my father's very strong. He's up there telling jokes, and he's very strong. He's doing fine ... We're just making sure to hold on to him as long as we can. That's what's most important."