Nine employees at Minnesota Correctional Facility–Stillwater were taken to the hospital on Thursday after being exposed to a "stronger-than-expected" dose of synthetic marijuana being smoked by an inmate, causing them to fall ill.

Nine staff members at the Minnesota Correctional Facility in Stillwater were treated at a hospital and released Thursday after being exposed to a synthetic drug, according to the state Department of Corrections.

The Department of Corrections says the staff members were brought to the hospital out of "an abundance of caution."