PD James, a British crime novelist who has written over 20 books, has died at the age of 94.

Her agent announced that she died in England "peacefully at her home in Oxford" on Thursday morning, reports BBC News.

James sold millions of books worldwide throughout her five-decade career. However, she was most known for her novels "The Children of Men," "The Murder Room" and "Death Comes to Pemberley."

Her UK publisher Faber & Faber released a statement following her death, saying: "It is difficult to express our profound sadness at losing P. D. James, one of the world's great writers and a Faber author since her first publication in 1962. She was so very remarkable in every aspect of her life, an inspiration and great friend to us all. We will miss her hugely," reports CNN.

British Prime Minister David Cameron also expressed remorse for the loss of the author, tweeting "Saddened to hear of the death of P.D. James, one of the UK's greatest crime writers, who thrilled and inspired generations of readers."

Last year, the novelist stated that she was writing another detective story as she found it "important to write one more," reports the BBC.

"With old age, it becomes very difficult. It takes longer for the inspiration to come, but the thing about being a writer is that you need to write," she said. "I hope I would know myself whether a book was worth publishing. I think while I am alive, I shall write. There will be a time to stop writing but that will probably be when I come to a stop, too."

Nicknamed "the Queen of Crime," many of her books featured the protagonist detective Adam Dalgliesh.  In 1986, the New York Times described him "a dedicated professional policeman, supremely efficient, sensitive but with reticence verging on coldness in personal matters." The Dalgliesh mysteries include "The Black Tower," "A Taste for Death," and "Death in Holy Orders."

During an interview with the Guardian, James admitted that she would have made the detective to be a woman if she was creating the character in modern times.

"If I was starting now, I would almost certainly have a woman professional police officer" as the main character, James said. "But when I began, in the late '50s, it was a very different world. Women in the police force mostly dealt with issues concerning women and children. I don't think they were even in the detective force, so I had no choice about sex."