The Catholic Archdiocese of Philadelphia has suspended 21 priests, after a grand jury report revealed yet another cover-up of predatory priests.

The mass suspension was the single-most sweeping in the history of the sexual-abuse scandal in the Roman Catholic Church in the United States, said Terence McKiernan, president of BishopAccountability.org, which archives documents from the abuse scandal in dioceses across the country.

The archdiocese’s action follows a damning grand jury report issued Feb. 10 that accused the archdiocese of a widespread cover-up of predatory priests, stretching over decades, and said that as many as 37 priests remained active in the ministry despite credible accusations against them.

Of those 37 priests, 21 were suspended; three others already had been placed on administrative leave after the grand jury detailed accusations against them. Five others would have been suspended, the church said in a statement, but three are no longer active and two are no longer active in the Philadelphia Archdiocese. The church said that in eight cases, no further investigation was warranted.