She was 76 years old.
“Today we sisters witnessed a tragedy. We lost our beautiful mother to mental illness. We are shattered,” Ashley Judd said in a statement on Twitter. Ashley Judd’s publicist has verified her statement to CNN.
“We are dealing with deep sadness and know we loved her and her fans,” the statement added. “We are in uncharted territory.”
Naomi and her daughter Winona began singing together as a professional act in the early 1980s, eventually producing a string of blockbuster songs, including “Mama Is Crazy” and “Love Can Build a Bridge” and selling over 20 million records.
Youngest daughter Ashley Judd later became a celebrity in her own right as an actress.
The Judds completed what was billed as a farewell tour in 2011, but earlier this year announced a 10-date “final round” that was set to begin in September.
They performed publicly together for the first time in years earlier this month at the CMT Music Awards.
After the birth of her two daughters, the family moved to Tennessee, where Naomi Judd worked as a nurse. By 1980, she and Wynonna began pursuing a musical career, appearing on a local morning show, according to the site.
Their first single, “I Had a Dream (To the Heart)”, released in 1983, reached number 17 on the Billboard country chart. Their next song, “Mama He’s Crazy,” became the #1 song on country radio, according to the website, and The Judds won their first Grammy in 1984.
Their music has been described by the Country Music Hall of Fame as having “distinctive harmony”, with “strong” lead vocals and vocal accompaniments with elements of “folk, blues and family harmony”.
That same year, she wrote a book, “River of Time: My Descent into Depression and How I Raised with Hope,” explaining her struggles.
Following news of her death, artists including country stars Carrie Underwood and Travis Treat shared their regards on social media.
CNN’s Lisa Ripers France contributed to this report.