By the CNN Wire Staff

Philadelphia (CNN) - Twenty-one priests have been placed on administrative leave following a review of suspected child sexual abuse by members of the Catholic Church in Philadelphia, according to a statement from the city's archbishop.

The church investigated 37 priests identified in a grand jury report as remaining in "active ministry with credible allegations of child sexual abuse," according to Cardinal Justin Rigali.

In addition to the 21 announced Tuesday, three other priests have already been placed on administrative leave after the report was released in February, Rigali said.

Five others would have been subject to administrative leave, he added, but one was already on leave and two others are considered "incapacitated" and have not been in active ministry. Two other priests no longer serve in the Archdiocese of Philadelphia, but the church has "notified the superiors of their religious orders and the bishops of the dioceses where they are residing," he said.

"I want to be clear: These administrative leaves are interim measures," Rigali said in a written statement. "They are not in any way final determinations or judgments."

The cardinal added that he wished "to express again my sorrow for the sexual abuse of minors committed by any members of the church, especially clergy."

"I am truly sorry for the harm done to the victims of sexual abuse, as well as to the members of our community who suffer as a result of this great evil and crime," he said.

In February, three Philadelphia priests and a parochial school teacher were charged with raping and assaulting boys in their care, while a former official with the Philadelphia Archdiocese was accused of allowing the abusive priests to have access to children, the city's district attorney's office said.

CNN Senior Vatican Analyst John Allen said the charges against the former church official appeared to be unprecedented and could have national implications.

"This is apparently the first time that a Catholic leader has been charged criminally for the cover-up as opposed to the abuse itself," he said. "It sends a shot across the bow for bishops and other diocesan officials in other parts of the country, who have to wonder now if they've got criminal exposure, too."

Edward Avery, 68, and Charles Engelhardt, 64, were charged with allegedly assaulting a 10-year-old boy at St. Jerome Parish from 1998 to 1999.

Bernard Shero, 48, a teacher in the school, is charged with allegedly assaulting the same boy there in 2000, Philadelphia District Attorney Seth Williams said at a press conference in February.

James Brennan, another priest, is accused of assaulting a different boy, a 14-year-old, in 1996.

Monsignor William Lynn, who served as the secretary for clergy for the then-Philadelphia Archbishop Anthony Bevilacqua, was charged with two counts of endangering the welfare of a child in connection with the alleged assaults, Williams said.

From 1992 until 2004, Lynn was responsible for investigating reports that priests had sexually abused children, the district attorney's office said.

The grand jury found that Lynn, 60, endangered children, including the alleged victims of those charged last week, by knowingly allowing dangerous priests to continue in the ministry in roles in which they had access to kids.

Avery, Engelhardt and Shero were charged with rape, indecent sexual assault and other criminal counts following the results of the grand jury investigation of clergy sexual abuse, Williams said. The names of the alleged victims, who are now in their 20s, have not been publicly released.

The grand jury believed that more than 30 priests remained in ministry in Pennsylvania despite solid, credible allegations of abuse, according to Williams.

Williams on Tuesday said Rigali's actions "are as commendable as they are unprecedented."

"Going forward, in cases involving allegations of abuse by clergy, my office and the Philadelphia police will investigate, and where appropriate we will charge and prosecute. I intend to use the resources of this office to the greatest extent possible to protect the children of Philadelphia," Williams said in a statement.

"In those cases where allegations are not prosecutable because of the statute of limitations or some other reason, we encourage the Archdiocese to take the necessary and proper steps to protect the children for whom they are responsible, as they have done here."