CANON CITY, COLORADO, JANUARY 7, 2005--A view of the outside of the maximum security Colorado state penitentiary in Canon City where the most hardened criminals stay. (DENVER POST PHOTO BY GLENN ASAKAWA)

COVID-19 has sickened at least 24 inmates at Colorado State Penitentiary near Cañon City, in the latest outbreak to hit the state prison system.

Testing of inmates and staff members is underway and expected to continue for several weeks to determine how widely the coronavirus has spread through the facility, Colorado Department of Corrections spokeswoman Annie Skinner said. The maximum-security prison — which formerly housed Colorado's shuttered death row — holds about 750 inmates.

It is the second largest active outbreak among the state’s prisons, behind the Buena Vista Correctional Complex in Chaffee County, which has 125 active infections among inmates, according to the latest data available.

The prison system’s largest outbreak was reported in April at Sterling Correctional Facility in northeastern Colorado, where 564 inmates tested positive for the virus, including three who died. The remaining inmates at Sterling have since recovered, prison data show.

Denver Women’s Correctional Facility has one active case of COVID-19 and Arrowhead Correctional Center near Canon City has two active cases, according to a state prison database.