UPDATE: Rosie O'Donnell tweeted that her daughter has been found and is safe.
Rosie O'Donnell is usually known for her fun sense of humor, but on Tuesday the comedian tweeted some troubling news about her 17-year-old daughter, Chelsea O'Donnell.
"CHELSEA O'DONNELL MISSING," she wrote, along with a link to a longer website post with more details about where she was last seen.
"Nyack, New York police authorities have been looking for her in the Rockland County area since Sunday, August 16. She was last seen Tuesday, August 11. She was wearing a black sweatshirt hoodie, dark ripped blue jeans, women's grey converse sneakers and a black backpack. Chelsea has a large tattoo on her right side of a dream catcher with the word 'Breathe.' She left home with her 6 month old therapy dog named Bear. The dog is a 9 lbs brown and black terrier. Chelsea stopped taking her medicine and is in need of medical attention," the post revealed.
O'Donnell, 53, also posted a photo of Chelsea and her dog. O'Donnell says her daughter may be in New York City -- about 25 miles south of her home in Nyack, New York.
A source told "Entertainment Tonight" the family doesn't think foul play is to blame; they think Chelsea ran away from home.
The insider did not specify which medication Chelsea is on -- though it's believed to be for a mental health condition, according to ET.
Chelsea is O'Donnell's adopted daughter with her ex, Kelli Carpenter. The former host of "The View" has five children -- Parker, Chelsea, Blake, Vivienne and Dakota.
O'Donnell parted ways with the daytime chat show earlier this year, saying she wanted to focus on her children following her split from Michelle Rounds, her wife of nearly three years.