A third California state prison has had an inmate die of suspected coronavirus as fatalities spread beyond what had been the prisons’ epicenter for such deaths, officials said Friday.

An inmate from Chuckawalla Valley State Prison near Blythe in Riverside County died Thursday at an outside hospital from what appears to be coronavirus complications, officials said, although the exact cause of death has not yet been determined.

It was the prison system’s 15th virus-related inmate death, with 13 of those at the California Institution for Men in Chino. Officials said the first death outside that prison came Tuesday, when an inmate from the California Institution for Women in Corona, east of Los Angeles, died at an outside hospital.

Chuckawalla Valley has 990 inmates who are positive for the coronavirus.

Statewide, more than 2,440 inmates have tested positive and more than 660 have recovered.

Two corrections employees have died. Nearly 500 employees have tested positive, and more than 230 of them have returned to work.

For most people, the coronavirus causes mild or moderate symptoms, such as fever and cough that clear up in two to three weeks. For some, especially older adults and people with existing health problems, it can cause more severe illness, including pneumonia and death. The vast majority of people recover.