Fisher's daughter, Billie Lourd, released a statement through her spokesman saying Fisher died Tuesday just before 9 a.m. PT.
"...she was loved by the world and she will be missed profoundly. Our entire family thanks you for your thoughts and prayers."
ABC News confirmed Fisher's family was by her side, including her mother, actress Debbie Reynolds.
Reynolds on Facebook thanked fans for embracing "the gifts and talents of my beloved and amazing daughter" and for their help in "guiding her to her next stop."
Fisher went into cardiac arrest on Friday aboard a flight from London to Los Angeles. She was then placed on a ventilator. Reynolds described Fisher as being "stable" over the weekend.
Fisher's brother, Todd Fisher, told Eyewitness News it had been a rough few days for the family.
"We've just seen her pull out so many times and survive so many things that there was no way to talk," he said in a phone interview. "I hope people don't think our silence was anything more than just us praying for the best."
He added that his sister was very giving. She was a world-class shopper who got the greatest joy buying gifts for her loved ones.
"It was one of the most amazing things about her...," he added.
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Fisher made her feature film debut opposite Warren Beatty in the 1975 hit "Shampoo." She found enduring fame as Princess Leia in the original "Star Wars" films, the first of which was released in 1977.
Fisher reprised that role almost 40 years later in the 2015 film "Star Wars: The Force Awakens." Fisher's work in the next "Star Wars" film, due out in December of 2017, is already done.
She has also authored several books and had been touring to promote her latest work, "The Princess Diarist," which made headlines when it was released in November for its disclosure that she had an affair with then-married actor Harrison Ford during filming of the original "Star Wars."
Fisher sometimes worked as a "script doctor," fixing screenplays that needed some help.
The starlet also wrote the book and the screenplay for "Postcards from the Edge," a semi-autobiographical story about an actress with substance abuse problems who moves back in with her mother.
In 1980, she had a role opposite John Belushi in "The Blues Brothers," and a year later, she was working with Chevy Chase in "Under the Rainbow."
In 1989, she served up some of the laughs in the classic comedy, "When Harry Met Sally."
MORE: Carrie Fisher describes filming Star Wars in rare 1977 interview
In England, Fisher had just finished shooting new episodes for Amazon's streaming series, "Catastrophe," before her health crisis.
Fisher is survived by her daughter, Lourd, brother, Todd Fisher, and her mother, Reynolds -- all a close-knit family.
"We've really been close our whole lives and it's a very strange place to be looking at the world without her," said her brother.
Fisher fit a lot into her 60 years. To borrow a phrase from "Star Wars," she was a "force."
"She also left a lot of her with us," an emotional Todd Fisher said. "Her words will go on long after we've all left."
The Associated Press contributed to this report.
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