Joni Sledge, one of the founding members of R&B disco group Sister Sledge, has passed away at the age of 60.

The singer, best known for her group's 1979 Grammy-nominated dance anthem "We Are Family," which hit No. 2 on the Billboard Hot 100, was found dead in her home in Phoenix on Friday, March 10, according to a statement made by her publicist Biff Warren to CNN.

Her cause of death is still unknown, and the Sledge family was shocked by her passing as the vocalist had not been ill, Warren said.

"Yesterday, numbness fell upon our family. We are saddened to inform you that our dear sister, mother, aunt, niece and cousin, Joni passed away yesterday. Please pray for us as we weep for this loss. We do know that she is now eternally with Our Lord," the band wrote in a statement on their web site.

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