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.

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.

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