Joni Sledge, who belonged to the four-sister disco-era group Sister Sledge, best known for its No. 1 hit We Are Family, died Friday at her home in Phoenix, a spokeswoman for the group announced. She was 60.

No cause of death has been announced.

"Yesterday, numbness fell upon our family," said the Sledges in a statement Saturday. "Pray for us as we weep for the loss of our sister, mother, aunt, niece and cousin Joni Sledge. We thank you for privacy as we hurt for her presence, but also for embracing her radiance and the sincerity with which she loved life."

Joni Sledge was born September 13, 1956, to tap dancer Edwin Sledge and actress Florez Sledge. She was the second eldest of the four sisters who formed their group in Philadelphia in 1971, working first as backup singers and then stars in their own right after they connected with Nile Rodgers and Bernard Edwards, the leaders of the disco group Chic.