WALLA WALLA -- A unit at Washington State Penitentiary in Walla Walla is on lockdown after an offender-involved assault Friday.
One inmate received minor injuries in the incident about 3 p.m. in a common area of one of the prison's four close-custody living units.
The unit houses 187 offenders, according to a news release.
Staff responded immediately, according to the release. A weapon was found on the floor after the offenders were under control.
The injured inmate was treated by on-site medical staff, the release said. Prison officials are investigating the cause of the incident.
The lockdown will continue through the weekend.