0 of 0

Updated at 8:40 a.m. ET Sept. 28

Pope Francis, in a previously unannounced stop, met with victims of clergy sex abuse in Philadelphia, as the pontiff is wrapping up a six-day visit to the U.S. that will culminate with a huge Mass this afternoon.

Meeting with 300 bishops, Francis said he had met with the sex abuse survivor group Sunday morning.

"It continues to be on my mind that the people who had the responsibility to take care of these tender ones, violated that trust and caused them great pain," he said, adding "God weeps."

The pope added that the abuse "cannot be maintained in secret. And I commit to a careful oversight to ensure that youth are protected."

The Vatican, in a statement, says Francis met with three women and two men who had been abused as children. It said that each was accompanied by a family member or someone close and that the pope listened and expressed solidarity in sharing in their suffering.

"He renewed the commitment of the Church to the effort that all victims are heard and treated with justice, that the guilty be punished and that the crimes of abuse be combated with an effective prevention activity in the Church and in society," the statement said.

Francis has decided on a new Vatican tribunal to prosecute bishops who covered up abuse and shielded pedophile priests instead of turning them over to police, according to The Associated Press.

Francis also talked of marriage during his remarks to U.S. bishops, who the AP says have called the Supreme Court's same-sex marriage "a tragic error" and a "profoundly immoral and unjust decision."

Religion News Service reports that:

"Without mentioning gay marriage, he noted that civil marriage and Christian sacramental marriage no longer share a common meaning, as they once did. Yet while recognizing the profound changes taking place, he warned bishops against pointing fingers at their flock or wallowing in nostalgia." 'Should we blame our young people for having grown up in this kind of society? Should we condemn them for living in this kind of a world?' Francis said. 'Should they hear their pastors saying that "it was all better back then," the world is falling apart and if things go on this way, who knows where we will end up?" No, I do not think that this is the way.' "

The remainder of the pope's schedule today concludes a busy itinerary for the pontiff's visit that will have seen him celebrate Mass before millions in Philadelphia, Washington, D.C., where he also spoke to a joint meeting of Congress and New York, where he addressed the United Nations General Assembly.

After his meeting with bishops, Francis visited the Curran-Fromhold Correctional Facility, where he encouraged inmates to get their lives back on track. The pontiff invoked the parable of Jesus washing the feet of the apostles before the Last Supper and criticized prison systems that punish and humiliate prisoners rather than help rehabilitate them.

The huge outdoor Mass today will be on Philadelphia's Benjamin Franklin Parkway just before the pope flies back to Rome.

Prior to the afternoon mass, he is expected to head to Curran-Fromhold Correctional Facility, "where he'll visit with 100 inmates — a cross-section of suspected killers, rapists, mobsters. He's expected to offer them words of hope, forgiveness and redemption," the AP writes.

"His mission is the marginalized, the forgotten," prison spokeswoman Shawn Hawes said, according to the AP. "From our understanding, he wants those who are in custody to know that they are not forgotten and they can be redeemed."

On Saturday, the pope largely discarded his prepared text and spoke off-the-cuff at the World Meeting of Families conference, calling the family "a factory of hope."

"In the family, there are indeed difficulties" and children bring challenges, too, he said.

Copyright 2016 NPR. To see more, visit http://www.npr.org/.