Updated

The injury toll in a California prison riot has risen to 13.

The riot occurred Wednesday at the California State Prison, Sacramento in Folsom.

Authorities say one of the injured was shot by correctional officers.

Corrections spokesman Terry Thornton says the disturbance inside a prison yard broke out shortly after 11 a.m.

In addition to the shot inmate, 12 others were treated at a hospital for stab and slash wounds. Authorities earlier said 11 inmates were injured.

Prison officials said 60 inmates were involved, but have not discussed what provoked it.

Thornton says officers tried to quell the riot by firing non-lethal rounds as well as firing six shots from a rifle. The state plans to investigate the decision to use potentially deadly force, which is a standard procedure.