Suicide

9:00pm PT -- Law enforcement sources tell TMZ Fiona died at home Tuesday. Our sources say authorities were called to the home at 12:10 am.

Rob Lowe’s brother, Chad Lowe and his wife, Kim Painter, are mourning the devastating loss of their teenage daughter … Fiona who died at 13 years old.

The family tells TMZ in a statement, “We are deeply heartbroken by the loss of our beloved Fiona.”

Chad and Kim remembered their daughter as a loving, smart and creative young girl who loved to dance, saying she was adored by her sisters and deeply loved by her parents.