"Everyone at God's Love We Deliver is profoundly saddened to hear about her accident," Karen Pearl, president of the organization, said in a statement to ABCNews.com before Richardson's death. "As we hope for the best, our thoughts and prayers are with her, Liam, and their entire family at this difficult time."
Richardson's sister, Joely, stars in the TV series "Nip/Tuck."
Richardson starred in many films, including "The Parent Trap," "Maid in Manhattan," "A Month in the Country," "Gothic" and "Nell." But her chief experience was in theater. She was trained at London's Central School of Speech and Drama and won a Tony Award in 1998 for playing Sally Bowles in "Cabaret." As a tribute to her, the theaters of Broadway said they would dim their lights Thursday night.
Sher met her husband in 1984 while filming the TV mini-series "Ellis Island," but their relationship didn't blossom until 1993, when they reunited on Broadway for a revival of "Anna Christie." Their on-stage chemistry was too strong to ignore, and shortly after "Anna Christie's" run, Richardson separated from her husband, producer Robert Fox. She and Neeson married in 1994.
Richardson acted with her legendary mother at multiple points in her career. In January, Richardson and Redgrave played the roles of mother and daughter in a one-night benefit concert version of "A Little Night Music," the Stephen Sondheim-Hugh Wheeler musical, on Broadway.
The two also acted alongside each other in the 1985 theatrical revival "The Seagull" and the 2007 movie "Evening." In a 2003 interview with UK newspaper The Guardian, Richardson talked about taking on the same profession as her mother.
"I don't know if I could ever put myself in the same category as her," she said. "She is one of the greatest actresses of our time, so I'm not sure I would put myself in that bracket."
She expanded further in a 2005 interview with The Independent.
"I know the pressures of being the daughter of a great actress," Richardson told the newspaper. "But it's inspiring. You learn so much that other people don't get to learn until later on. My father being a director, I learnt a real work ethic. You think: 'One day, I'd like to be as good as that.' But when I was starting out professionally, I had a level of attention put on me that I didn't deserve or wasn't ready for. And it was hard, particularly in England, to make my way. That's partly why I moved to New York, where you can be who you are for your work and not so much to do with family baggage."
But in the same interview, Richardson talked about how she didn't want her sons going into acting.
"They'd be the sons of a great actor," she told The Independent. "And that's quite a gorilla to carry on your back. This profession is very tough and not many people make it , and even if you do, then you can still get slapped in the face constantly. So I hope they do something else -- but if they're determined, so be it."
Additional reporting contributed by ABC News' Sharyn Alfonsi, Monica Escobedo, Emily Friedman, Lindsay Goldwert and Luchina Fisher.