By Jen Heger - Breaking Celebrity News Assistant Managing Editor

UPDATE: "I want to reassure everyone (inc all sudden medical experts) that Mother is fine but is resting up in AZ on the orders of a doctor, not us," Jermaine Jackson tweeted Sunday morning. "This is our mother and her health is paramount. We are not inventing or plotting anything. We are following doctor's advice. Period."

Katherine Jackson has been reported missing to the Los Angeles County Sheriff's Department after her grandchildren, Paris, Prince, and Blanket were unable to reach her all week, Breaking Celebrity News has confirmed.

"I can confirm that a missing person's report was filed this evening by Mrs. Katherine Jackson's nephew, Trent Jackson, after he was unable to see her or reach her for a week. The report will be referred to the Homicide/Missing Persons Unit, and they will be handling the investigation," Lt. Josh Thai told Breaking Celebrity News exclusively.

And a source close to the situation tells us exclusively, "The kids are being taken care of by their nanny. Paris is absolutely beside herself with worry. She lost her father three years ago, and not to know if her grandmother is ok is just more than she can bear."

As we previously reported Katherine Jackson was blindsided by news a letter had been written by several of her children to the executors of Michael's estate, demanding their resignation. The letter, allegedly from Janet, Rebie, Tito, Randy, and Jermaine, demanded that executors John Branca and John McClain resign immediately because they (the Jackson siblings) believe that the late singer's will was a fake.