Carrie Fisher, best known for her iconic role as Princess Leia in Star Wars, had a heart attack on a flight on Friday.

An unnamed source told CBS News that Fisher went into cardiac arrest on a flight from London to Los Angeles, where she was going for her book tour.

Fisher received CPR on the plane, and was treated by paramedics immediately after landing in Los Angeles.

The news was confirmed by Fisher’s brother, Todd Fisher. Fisher said she received excellent medical care, but did not give additional details about any underlying medical issues.

Fisher has been open about her past struggles with drug and alcohol abuse, as well as mental illness. In 2013, she was hospitalized due to an incident relating to bipolar disorder.

Harrison Ford on Carrie Fisher’s Heart Attack

Fellow co-star of Star Wars, Harrison Ford, came out with a statement regarding the heart attack. The statement was released on Saturday.

“I’m shocked and saddened to hear the news about my dear friend,” Ford said to The Hollywood Reporter. “Our thoughts are with Carrie, her family and friends.”

Mark Hamill, who played Luke Skywalker in the original films, shared a tweet about Fisher. “As if 2016 couldn’t get any worse… sending all our love to @carrieffisher,” he wrote.

as if 2016 couldn't get any worse… sending all our love to @carrieffisher

— Mark Hamill (@MarkHamill) December 23, 2016