Minnesota Correctional Facility - Stillwater, the state's largest prison, is on temporary lockdown after several staff members were possibly exposed to synthetic drugs on Thursday.

Nine workers at a Minnesota prison fell ill and were hospitalized after being exposed to unknown synthetic substances possessed by men who are incarcerated.

Several Stillwater prison staff members were taken to the hospital Thursday following an incident that put the facility into a lockdown, Minnesota Department of Corrections officials said. “Several staff were taken to the hospital out of an abundance of caution,

A spokesperson for the Federal Bureau of Prisons confirmed Thursday that the Waseca Federal Correctional Institution was placed on "modified operations" on Sept. 4 after nine inmates were sent to a local hospital for "exhibiting signs of drug use.