British actress Natasha Richardson's family have gathered at her bedside in New York's Lenox Hill Hospital.
The 45-year-old is in a critical condition following a skiing accident in Canada on Monday.
She was flown by private jet to the US on Tuesday, accompanied by her actor husband Liam Neeson.
Their sons, Richardson's mother Vanessa Redgrave and sister Joely all visited the hospital. A family spokesperson said they are "very distressed".
Richardson initially appeared unhurt after an "undramatic accident" on a beginners' run at the resort of Mont Tremblant.
The Tony award-winning actress was taken ill an hour later.
She was later taken to the nearby Centre Hospitalier Laurentien before being transferred to the larger Hopital du Sacre-Coeur, in Montreal.
Mont Tremblant ski resort spokesperson Lyne Lorties describes what happened
Neeson left the set of his latest film, Chloe, which is shooting in Toronto, to be at his wife's bedside.
The Manhattan hospital to which Richardson has been transferred is near the family home.
An update on her condition is expected later on Wednesday.
The statement from the Mont Tremblant resort in Canada said the actress "fell in a beginners' trail while taking a ski lesson".
"She was accompanied by an experienced ski instructor who immediately called the ski patrol," it continued.
"She did not show any visible sign of injury but the ski patrol followed strict procedures and brought her back to the bottom of the slope and insisted she should see a doctor."
Richardson and Neeson married in 1994 after appearing in the film Nell.
Part of the Redgrave acting dynasty, Richardson is the daughter of Redgrave and director Tony Richardson, and the sister of Nip/Tuck star Joely Richardson.
She has starred in a number of Hollywood films and acted opposite an 11-year-old Lindsay Lohan in 1998's The Parent Trap.
But she is better known for her work on the stage, winning a Tony award in 1998 for her starring role in Sam Mendes' Broadway production of Cabaret.