Heche is being kept alive in a coma on life support as organ donation is being considered as an option, her spokesperson said.
The statement issued on behalf of Heche's family and friends read:
"We want to thank everyone for their kind wishes and prayers for Anne's recovery and thank the dedicated staff and wonderful nurses that cared for Anne at the Grossman Burn Center at West Hills hospital.
Unfortunately, due to her accident, Anne Heche suffered a severe anoxic brain injury and remains in a coma, in critical condition. She is not expected to survive.
It has long been her choice to donate her organs and she is being kept on life support to determine if any are viable.
Anne had a huge heart and touched everyone she met with her generous spirit. More than her extraordinary talent, she saw spreading kindness and joy as her life's work - especially moving the needle for acceptance of who you love. She will be remembered for her courageous honesty and dearly missed for her light."
Heche crashed her car last week, apparently driving at high speed before losing control and smashing through the walls of a home in the Mar Vista neighborhood of Los Angeles, setting the car and home on fire. A woman inside the home and her pets escaped serious injury but her house was severely damaged.
Shortly after the crash, Heche slipped into a coma and was listed in critical condition.
Police later tested her blood and determined she was likely under the influence of a controlled substance while she was behind the wheel.
Anne Heche slipped into coma, is in critical condition after fiery Mar Vista car crash, rep says
Heche first rose to prominence on the soap opera "Another World," from 1987 to 1991 winning a Daytime Emmy for her role. In the 1990s she became a popular choice for Hollywood, co-starring in films such as "Donnie Brasco," "Volcano" and "Return to Paradise."
Her relationship with Ellen DeGeneres during the late 1990s heightened her fame, though she lamented that the publicity seemed to harm her career.
In the fall of 2000 soon after the two broke up, Heche was hospitalized after knocking on the door of a stranger near Fresno. Authorities said she had appeared shaken and disoriented, and spoke incoherently to the residents.
In a memoir released the following year, "Call Me Crazy," Heche talked about her lifelong struggles with mental health and a childhood of abuse.
She was married to camera operator Coleman Laffoon from 2001 to 2009. The two had a son together. She had another son during a relationship with actor James Tupper, her co-star on the TV series "Men In Trees."