Natasha Richardson dies after Quebec skiing accident
A family spokesperson made the announcement Wednesday evening.
"Liam Neeson, his sons and the entire family are shocked and devastated by the tragic death of their beloved Natasha," spokesman Alan Nierob said in a statement.
"They are profoundly grateful for the support, love and prayers of everyone, and ask for privacy during this very difficult time."
The statement did not give details about the cause of death.
Richardson, 45, was a celebrated film, TV and stage actress with prolific credits on both sides of the Atlantic. She came from an esteemed family of British actors.
Her maternal grandparents were Sir Michael Redgrave and Rachel Kempson, and her Oscar-winning parents were Vanessa Redgrave and the late Tony Richardson.
Her younger sister, Joely Richardson, is an actor, as are her aunt Lynn Redgrave, uncle Corin Redgrave and aunt Kika Markham.
Though Richardson and her husband, Irish actor Liam Neeson, were based in the United States, where their teenaged sons Micheal and Daniel were born, she trained at London's Central School of Speech and Drama.
A familiar face for movies such as The Handmaid's Tale, The Comfort of Strangers, Nell and The Parent Trap, Richardson is most noted for her extensive stage career.
Theatre accolades began flowing in 1986, when she was dubbed the most promising newcomer by the London Drama Critics Circle for a turn in The Seagull opposite her mother.
By 1998, when she starred as Sally Bowles in Sam Mendes' revival of Cabaret, Richardson was awarded a raft of best actress trophies, including Tony, Outer Critics circle and Drama Desk Awards.
After starring in a one-night benefit concert performance of Stephen Sondheim's A Little Night Music with her mother in January, Richardson had been slated to reprise the role in a planned upcoming production.
She had also been set to star on Broadway in a December revival of August Strindberg's Miss Julie, along with Philip Seymour Hoffman.
Actress 'seemed all right'
On Monday afternoon, Richardson was taking a lesson on a beginner's slope at Quebec's Mont Tremblant ski resort, north of Montreal.
The actress, who was not wearing a helmet, suffered what initially appeared to be a benign fall, not hitting anyone or anything else, according to the resort.
"She showed no injuries," Mont Tremblant spokeswoman Lyne Lortie told CBC News on Tuesday. "She was talking. She seemed all right. But [the ski patrol] have to follow strict procedures, so they brought her back to the bottom of the slope."
Neeson immediately left the Toronto set of the Atom Egoyan film Chloe to join her Monday evening in Montreal.
Around midday on Tuesday, the actress was taken by private plane to New York, where the couple lives with their sons.
Family members — including the two boys and Richardson's mother, Vanessa Redgrave — were seen arriving at Manhattan's Lenox Hill Hospital on Tuesday evening.
With files from the Associated Press