Protester yells "shame on you" as Cardinal Donald Wuerl addresses priest sex abuse

Tensions erupted during a Catholic mass as the Archbishop of Washington, D.C. addressed the clergy sex abuse scandal. A protester interrupted Cardinal Donald Wuerl Sunday as he pleaded for loyalty to Pope Francis.

Wuerl has been facing calls to resign since a scathing grand jury report revealed abuses that occurred during his time as head of the Pittsburgh diocese. The heckler was reportedly upset with the Catholic Church's lack of transparency throughout decades of alleged sexual abuse. The disruption came when Cardinal Wuerl asked the congregation to keep Pope Francis in their prayers.

"Shame on you!" the protester yelled.

After the interruption during his Sunday sermon, Cardinal Wuerl apologized for how he and the Catholic Church handled the clergy sexual abuse scandal, reports CBS News' Nikki Battiste.

"Yes, my brothers and sisters, shame. I wish I could redo everything over these 30 years," Wuerl said.

Last month, a Pennsylvania grand jury report found more than 300 Catholic priests abused more than 1,000 children since 1947 in six state dioceses.

Wuerl was not accused of misconduct, but he did oversee the Pittsburgh diocese during the time several abuses occurred.

Battiste spoke to the embattled cardinal about the clergy abuse scandal last month.

"How does it feel knowing children were sexually abused at the hands of priests under your watch?" Battiste asked.

"We're very, very sorry this happened and that's why we've taken the steps to see that it doesn't go on," Wuerl replied.

The church now faces another hurdle as a former papal ambassador to the U.S. is calling for the pope to step down. Archbishop Carlo Maria Viganò alleges Pope Francis willingly took a 2015 meeting with controversial Kentucky clerk Kim Davis who drew criticism for refusing to issue same-sex marriage licenses. The Vatican has maintained Davis was snuck in by Viganò and the pope did not know who she was.

"It is completely unprecedented for an ambassador from the Holy See to publicly accuse the pope of something like this. The Catholic Church normally operates behind closed doors, we never hear about these kinds of controversies," said Candida Moss, a professor of theology at the University of Birmingham.

Some supporters of Pope Francis believe Archbishop Viganò represents a conservative sect of the church that doesn't support Pope Francis' emphasis on inclusion of the gay community.  

In a press release Sunday, Cardinal Wuerl said: "Increasingly it is clear that he, the pope, is the object of concentrated attack."