Carrie Fisher has suffered a massive heart attack on a flight from London to Los Angeles.
The 'Star Wars' actress was helped by doctors and nurses, who happened to be on board and performed lifesaving CPR on the 60-year-old, best-known for playing Princess Leia.
In a dramatic exchange between the flight crew and air traffic control, the pilot described how fellow passengers were fighting to save her life.
He told controllers: "We have some passengers, nurses assisting the passenger. We have an unresponsive passenger. They are working on her right now."
Actress Anna Akana was on board the flight and tweeted that Fisher stopped breathing "for 10 minutes or so".
"So many thanks to the United flight crew who jumped into action, and the awesome doctor and nurse passengers who helped."
Paramedics arrived to meet the flight at Los Angeles international airport and Fisher was taken to an intensive care unit at UCLA Medical Centre.
Early reports suggested her condition had stabilised, but her brother Todd Fisher has subsequently been more cautious.
He told reporters: "We have to wait and be patient. We have so little information ourselves."
Mark Hamill, who starred with Fisher in the original Star Wars films wrote on Twitter: "As if 2016 couldn't get any worse... sending all our love to @carrieffisher."
as if 2016 couldn't get any worse... sending all our love to @carrieffisher
— Mark Hamill (@HamillHimself) December 23, 2016
Peter Mayhew, who is best known for playing Chewbacca, tweeted: "Thoughts and prayers for our friend and everyone's favorite princess right now.. @carrieffisher."
Thoughts and prayers for our friend and everyone's favorite princess right now.. @carrieffisher
— Peter Mayhew (@TheWookieeRoars) December 23, 2016
Mayhew later added Fisher was "stable".
Fisher had been on a tour to promote her new book, The Princess Diarist.
She also recorded an interview for 'The Graham Norton Show' while in the UK.
Norton wrote on Twitter: "carrieffisher Don't even think about it!! This planet needs you on it! Sending so much love xxx."
Carrie Fisher was just 19 when she was propelled to stardom in 'Star Wars'.
In her recent autobiography she said she had an "intense" affair with her co-star Harrison Ford during the making of the film.
She has also had well documented struggles with drugs and alcohol.
She wrote about her problems in detail in the semi-autobiographical 'Postcards From The Edge', which was later made into a film.
