TMZ broke the story ... Fisher was on a flight from London to LAX Friday when she suffered the heart attack 15 minutes before landing. People on the plane tell TMZ she appeared lifeless.

A passenger who's an EMT performed CPR on Carrie and once the flight landed, paramedics rushed her to UCLA Medical Center where she remained in intensive care until her death.

The family had said she was in "stable condition" but we're told she was not responsive after her medical emergency.

Carrie had been on a publicity tour for her new book, "The Princess Diarist." The book recently made headlines because she wrote about having an affair with co-star Harrison Ford while shooting the original 'Star Wars' movies.

Of course, Princess Leia was her iconic role, but Carrie also starred in "The Blues Brothers," "When Harry Met Sally," "Postcards from the Edge" and many, many more.

She famously battled substance abuse throughout her life. In 2013, she was hospitalized for complications from bipolar disorder.

Carrie is survived by her mother, Debbie Reynolds, daughter, Billie Lourde, brother, Todd Fisher, and sisters Tricia and Joely Fisher. Billie made an appearance alongside her mom in 'The Force Awakens.'