Valerie Harper, an American actress best known for her roles in "The Mary Tyler Moore Show" and "Rhoda," has been diagnosed with terminal brain cancer in 2013. And on Wednesday night, the 75-year-old actress was rushed to the hospital after she was found unconscious backstage during a performance of her musical, "Nice Work If You Can Get It," in a Maine playhouse.

According to the fire department who responded to an emergency call at 8:56 p.m., a 75-year-old woman was found unconscious backstage at the Ogunquit Playhouse in Maine. ET Online reported that the artistic director of the musical announced to the audience that Valerie Harper had fallen sick and would not be performing. And a source close to the situation said that Harper's health condition doesn't look good.

The Ogunquit Playhouse released Thursday a statement saying that Valerie Harper, who had been diagnosed with cancer since 2013, has been "resting comfortably" and is in the hospital for observation.

"Valerie Harper was taken to a local hospital as a precaution before her July 29 evening performance of 'Nice Work If You Can Get It,' at the Ogunquit Playhouse, after reporting that she was not feeling well," executive artistic director Bradford T. Kenney said, FOX News noted. "She is 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."

Aside from her terminal brain cancer, Valerie Harper also battled lung cancer in 2009. Last year, she announced that her cancer has not been cured, Yahoo! News has learned.

"In a way, it's a positive thing to know that a year's gone by and it's nowhere else in my body," she said. "So I am cancer free from the neck down, so far."

Since Valerie Harper was rushed to the hospital Wednesday night, a source close to the family said she is currently in a coma. But as per Time, Harper has been released from the hospital in York, Maine, where she was taken to.

Meanwhile, Valerie Harper has endured her ordeal and has been positive despite her experiences battling cancer.

"When I wake up in the morning, I don't say, 'Oh, I have cancer.' I say 'Another day. How you feeling? Good? Good,'" she told People in May.

As for now, Valerie Harper has been taken to a larger hospital for further treatment, Entertainment Weekly reported.