Days of unrest at the privately run Arizona State Prison-Kingman became a nightmare scenario as inmates rioted, trashed housing units and injured guards, prompting Gov. Doug Ducey to order an investigation Monday into the riot.

He told state Department of Corrections Director Charles Ryan to initiate the probe at the prison, which has a history of security issues.

"It is critical that we understand how these incidents occurred and how we prevent them in the future," Ducey said in a letter to Ryan. "The public also needs to know the facts and have assurances that prisons in our state — both state-run and privately run — are under control."

The unrest began July 1 in a minimum security unit when private corrections officers tried to stop an inmate-on-inmate assault. A full-blown riot broke out the next day in the medium security unit after an inmate became aggressive with a private corrections officer, according to Issa Arnita, a spokesman for Utah-based Management and Training Corp., which operates the prison.

The riot left some housing units so badly damaged that prisoners had to be moved to other facilities. Nine corrections officers suffered minor injuries in the first two days of unrest.

On July 4 more damage occurred when medium security inmates refused to follow orders and then went on a rampage. Four inmates were injured when state and private officers intervened.

More than 1,000 of the 2,500 prisoners at the prison have been moved to other facilities, including another Management and Training facility in Texas, a prison run by another contractor north of Tucson and a facility run by Pinal County, Corrections Department spokesman Andrew Wilder said.

A department assessment team was on site and will be leading a thorough investigation into the incidents, he added.

In 2010 three inmates escaped from the prison after a woman in a getaway car threw cutting tools over a fence. The inmates went on a violent crime spree that included killing an Oklahoma couple on a camping trip in New Mexico. The inmates were caught, tried and received new prison sentences.

Management and Training has continued to operate the prison despite a scathing report from Ryan that faulted the company for allowing security flaws and poor operational practices.

In January an inmate was sexually assaulted and beaten by other prisoners and died at a hospital three days later, according to a legal claim filed by his family. The legal action says emergency responders weren't notified for nearly two hours.

The inmate, Neil Early, was serving a five-year sentence for theft and possession of drug paraphernalia after becoming addicted to heroin and stealing video games. His father told The Associated Press that the prison was rife with violence and drugs.

State officials and Management and Training have not cited a cause for the problems in the medium-security unit. They also haven't provided a damage estimate. Wilder said windows were broken and security cameras and plumbing fixtures were destroyed.

Management and Training and its insurers will pay for repairs and compensate the state for response costs, Arnita said.

Arizona has about 43,000 inmates in prisons, including 7,500 in private facilities. The practice of using private prisons has been criticized by groups that contend operators cut costs at the expense of prisoners in order to improve profits.

Buster Johnson, a Mohave County supervisor who worked to have the prison located there, was particularly concerned about Friday's riot, in which prisoners rampaged out of control for hours before corrections and private prison staffers brought them under control.

"I'm worried about the possibility of the escape, especially when you have that many people rioting," he said. "We have a limited amount of men to control that many inmates without some kind of deadly force being used."

State police, Mohave County deputies and Kingman police provided perimeter security during the incidents. No security breaches were reported, Wilder said.

The Associated Press