(CNN) - Six staff members at a prison in Connecticut were taken to local hospitals for possible exposure to fentanyl, the potent synthetic opioid, the Connecticut Department of Correction said.
An ambulance was called to the Cheshire Correctional Institute, a state prison, at 9 a.m. on Tuesday to take a correctional officer in medical distress to the hospital, the department said in a statement.
About an hour later, a staff member from the facility's school system also began feeling unwell, the statement said, and then a school teacher and three more correctional officers reported feeling poorly.
All six staff members remained conscious and alert, and two have since been treated and released from the hospital, the statement said. No offenders exhibited any signs of fentanyl exposure.
The prison has been placed on lockdown, and the Connecticut State Police Hazmat team and the Department of Energy and Environmental Protection have reported to the facility, the statement said. The Department of Correction and Connecticut State Police are investigating.
The correctional institution has 428 current staffers and emphasizes rewards for deserving inmates, including in educational programming, its website states.
Fentanyl is a synthetic opioid that can be 50 to 100 times more powerful than other opioids like morphine, heroin and oxycodone, according to Lindsay LaSalle, senior staff attorney for the nonprofit Drug Policy Alliance.
That potency means that police, first responders and prison staffers can overdose or suffer health effects after even a minor encounter with the drug.
Synthetic opioids like fentanyl were the leading cause of opioid-related overdose deaths in the United States as of 2016, overtaking prescription drugs, according to a report published in JAMA.
Drug overdose deaths in the U.S. declined 5.1% in 2018, the first such drop in decades, according to preliminary data released by the US Centers for Disease Control and Prevention's National Center for Health Statistics.
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