Eighteen prison officers have been hospitalized after being exposed to a drug in a central Illinois correctional center.
Officers suffered lightheadedness, dizziness, vomiting and nausea after responding to a 'medical incident' involving an individual in custody who was under the influence of an unknown substance.
It comes as a union chief warned that incidents of officers becoming exposed to drugs in prisons is on the rise.
On Wednesday eighteen staff members from the John A Graham Correctional Center in Hillsboro received treatment at area hospitals, reports CBS news.
Eighteen prison officers have been hospitalized after being exposed to a drug in John A Graham Correctional Center in Hillsboro
The Graham Correctional Center is is a medium-security lockup for adult males that opened in 1980 with room for 1,596 inmates
Hillsboro Area Hospital has confirmed it treated eight patients from the center while St Francis in Litchfield said it has responded to a further nine patients from the facility.
Most have now been released but several are being kept for observation.
An undisclosed number of inmates were also treated in the health care unit of Graham Correctional Center which is around 65 miles northeast of St. Louis.
It is is a medium-security lockup for adult males that opened in 1980 with room for 1,596 inmates. It currently houses 1,328.
Illinois State Police are now working with Hazmat crews to determine what the substance is.
Union chief Anders Lindall has warned that incidents of officers becoming exposed to drugs in prisons is on the rise
The state department of corrections spokeswoman Naomi Puzzello said: 'All staff members who may have potentially encountered the unknown substance were also sent to a local hospital, as a precaution.
'All staff are stable currently and many have already been discharged.'
Anders Lindall of employee union American Federation of State, County and Municipal Employees Council 31 (AFSCME) said a union meeting was underway at the prison when the call went out and members broke up the gathering to transport colleagues to the hospital and provide other assistance.
He told CBS: 'The issue of exposure to harmful substances in prisons is increasing,'
'AFSCME has been sounding the alarm for months to tighten up the protocol for both incoming mail and visitor screening.'
One law enforcement official told KTVI in St. Louis, the sister station of CBS Champaign, Ill. affiliate WCIA-TV, that a call went out to local agencies for all available NARCAN to be delivered to the facility.
NARCAN is a medication commonly used to counter the effects of opioids.
Fox News says it has heard from local sources that the substance was Fentanyl, a highly powerful synthetic opioid - though experts have previously cast doubt on its potency