Grammy-winning jazz and pop singer Nancy Wilson died at her home in Pioneertown, California, on Thursday night.

Confirming the news to the Associated Press, her manager Devra Hall Levy said the 81-year-old singer passed away peacefully after a long illness. The exact nature of her illness remained unknown, but she was last hospitalized in 2008 after suffering complications of the lung.

After the news of death was became known, several fans took to Twitter to express their condolences.

“To lose Aretha Franklin and Nancy Wilson in the same year is such a massive loss of American Musical Groundbreakers. RIP Nancy Wilson, you were such a class act,” one user wrote.

“Nancy Wilson was one of my mom's favorite singers. She had had the voice and beauty of an angel. I am very sad to hear about her passing,” another fan wrote.

The singer, best known for songs such as "Guess Who I Saw Today" and "You Don't Know How Glad I Am," released eight albums in the 1960s. All the albums reached the top 20 on Billboard's pop charts.

"The music that I sing today was the pop music of the 1960s. I just never considered myself a jazz singer. I do not do runs and — you know. I take a lyric and make it mine. I consider myself an interpreter of the lyric,” she told the San Francisco Chronicle in 2010.

She retired from touring in 2011.

Wilson also had a prolific career in television, film and radio, and featured in shows such as "Hawaii Five-O," and ''Police Story." She was married twice, first to drummer Kenny Dennis, whom she divorced in 1970, and then to Wiley Burton, who died in 2008 after suffering from cancer.

She is survived by her daughters Samantha Burton and Cheryl Burton, son Kacy Dennis and her five grandchildren. A family statement said no funeral service would be held, in accordance with her wishes. However, a celebration of her life will likely will held in February.