ANCHORAGE, Alaska - The company that operates a Colorado prison for Alaska inmates said an error by a guard led to an uprising at the Hudson Correctional Facility.

A correctional officer in a central area electronically unlocked the cells of 41 inmates, Cornell Companies spokesman Charles Seigel told The Anchorage Daily News on Thursday. The mistake at 1:20 a.m. on April 14 allowed prisoners into corridors of the segregation unit, which holds problem inmates.

At least eight prisoners refused to go back into their cells and attempted to break into an office where two guards had barricaded themselves. A prison tactical team ended the disturbance six hours later. Some inmates suffered minor injuries.

The guard responsible for the breach has resigned. Seigel said he thought at least a couple of the instigators in the disturbance had been moved to a Colorado state prison.

The prison at Hudson, about 25 miles northeast of Denver, opened in November and holds about 900 inmates, all from Alaska. Cornell is looking into making improvements in the security system, Seigel said.

Corrections officials from Colorado and Alaska also have been investigating what happened.

Colorado's private prison monitoring unit and inspector general's office are involved, said Monica Crocker, spokeswoman for the Colorado Department of Corrections.