(CNN) At least 166 children were abused by dozens of Catholic priests in Colorado since 1950, a report released Wednesday says.

The 263-page report details decades of misconduct and reveals how it took nearly 20 years for one diocese to discipline priests accused of sexually abusing children.

"This is a dark and painful history," Colorado Attorney General Phil Weiser told reporters. "The culture going back decades was one where there was a reluctance to acknowledge and address wrongdoing."

The report was commissioned by the Colorado attorney general's office in agreement with the state's three dioceses to document sexual misconduct involving minors by priests.

For seven months, former US Attorney Bob Troyer reviewed more than 500 priest files and interviewed witnesses, victims, priests and law enforcement. In his findings, Troyer says most of the incidents took place in the 1960s and 1970s.

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