A grand jury in Pennsylvania has found that hundreds of children were sexually abused for more than four decades by priests belonging to the Catholic Diocese of Altoona-Johnstown.

The 147-page report was released by state Attorney General Kathleen Kane's office Tuesday that lists the widespread abuse involving at least 50 priests or religious leaders, according to Penn Live.

It showed that the Catholic bishops covered up the sexual abuses committed by the priests.

A search warrant issued in August last year uncovered a secret archive and confidential litigation files in filing cabinets and files at the administrative office of the diocese that point to the child sexual abuse. About 115,042 files were removed from the diocese including memos, letters and documents from Bishops James Hogan and Joseph Adamec, and statements and letters from sexual abuse victims, and correspondence with the offending priests.

According to the report, the late Monsignor Francis McCaa was "a monster" who groped and fondled the genitals of at least 15 boys including altar boys. He was assigned at the Holy Name Church in Ebensburg for more than 20 years.

Priest Joseph Gaborek, 70, was described in the report to be "particularly heinous example of the Diocese exercising authority and influence to cover up the sexual abuse of a child at the hands of a Diocesan priest."

He was assigned at the St. Michael's Church in West Salisbury and St. Mary's Church in Pocahontas in the 1980s where he recruited a 16-year-old boy to work at the churches and sexually abused him.

The Diocese of Altoona-Johnstown received a copy of the report.

"This is a painful and difficult time in our Diocesan Church," said the Rev. Mark L.Bartchak, bishop of the diocese. "I deeply regret any harm that has come to children, and I urge the faithful to join me in praying for all victims of abuse."

The report is the latest case of sexual abuse scandal involving the Catholic Church. In 2002, the Boston Globe reported abuse at the Boston Archdiocese, which became the basis for the movie "Spotlight," which won Best Picture at the Oscars.

A 2014 study commissioned by the Catholic Church showed that more than 4,000 U.S. priests faced sexual abuse allegations in the last 50 years involving more than 10,000 children, according to Penn Live.

The Catholic Church spent more than $2 billion between 2004 and 2013 in settlements, therapy for victims, support for offenders and attorney's fees.

Hogan and Adamec were leaders at the Altoona Diocese from the 1960s to 2011 and led the cover-up, the report said.

"The heinous crimes these children endured are absolutely unconscionable," said Kane at a press conference at the Blair County Convention Center. "These predators desecrated a sacred trust and preyed upon their victims in the very places where they should have felt most safe."

She said clergy leaders "failed in our society's most important task of protecting our children."

The report said the abusers cannot be prosecuted because either the abusers are already dead or the statute of limitations had already expired. It also said victims were unable to testify in court.

The grand jury recommended the lifting the statute of limitations for sexual offences against minors.