Valerie Harper was rushed to the hospital prior to a performance at the Ogunquit Playhouse on Wednesday.

The 75-year-old actress was scheduled to play Millicent Winter in Nice Work If You Can Get It when she was discovered unconscious backstage. Harper was taken by ambulance to York Hospital in York, Maine.

The Ogunquit Playhouse issued an update Thursday, assuring fans the star was "resting comfortably and "will remain in the hospital for observation for the time being."

"The audiences and all of us here at the playhouse are greatly enjoying our time with Valerie here in Ogunquit, and we are encouraged that she is feeling better," the venue's executive artistic director, Bradford T. Kenney, said.

Harper was diagnosed with terminal brain cancer in January 2013, and given just three months to live. The actress has since appeared on ABC reality competition Dancing with the Stars and said she was doing well and responding to treatments in April 2014.

Harper is best known for portraying Rhoda Morgenstern on CBS sitcom The Mary Tyler Moore Show and its spinoff, Rhoda, and Valerie Hogan on NBC series Valerie. She has guest starred on Melissa & Joey and 2 Broke Girls in the past year.