Joni Sledge, who with her sisters recorded the enduring dance anthem "We Are Family," has died at the age of 60, the band's representative said Saturday.
Sledge was found dead in her Arizona home by a friend on Friday, the band's publicist, Biff Warren, said.
The cause of death has not been determined. Warren said Sledge had not been ill.
"Yesterday, numbness fell upon our family. We welcome your prayers as we weep the loss of our sister, mother, aunt, niece and cousin," read a statement from the family.
Sledge and her sisters Debbie, Kim and Kathy formed the Sister Sledge in 1971 in Philadelphia.
Bernard Edwards and Nile Rodgers of the hit group Chic wrote and produced their album "We Are Family," and soon the women had their first major hit with disco jam "The Greatest Dancer," which became a top 10 hit in May 1979.
Their biggest hit came a month later with the title track, an infectious dance anthem that celebrated their familial connection with the refrain, "We are family, I got all my sisters with me." While it celebrated their sisterhood, the 1979 hit so also became an anthem for female empowerment and unity. It would become their signature hit, and was nominated for a Grammy. Both the song and album sold more than one million copies.
The women also had a hit with a cover of the Mary Wells song "My Guy" in 1982.
While Kathy had left the group for a solo career, the trio of sisters continued to perform and record, including a performance for Pope Francis in 2015.
Warren said their last performance together was at a concert in October.
Joni Sledge is survived by an adult son, her sisters and other relatives.
The Associated Press contributed to this report.