(CNN)A mixture of heroin and fentanyl left more than two dozen people sick Wednesday at the Ross Correctional Institution in Chillicothe, Ohio, officials said.
Combination of heroin and fentanyl sickened guards, inmate and nurses at Ohio prison, officials say
Authorities responded to the prison after reports that 29 people -- including 23 prison guards, four nurses and one inmate -- were overcome after being exposed to a substance, according to the state highway patrol. They were taken to Adena Regional Medical Center, the highway patrol's statement said.
"Several doses of Narcan were administered to victims, and an additional 300 Narcan doses are available at the facility," the statement said.
Narcan is commonly used to treat opioid overdoses.
The statement said the incident started with a report of an inmate with possible signs of a drug overdose.
When legitimately prescribed, fentanyl helps patients managing extreme pain, such as caused by cancer. It is typically dosed in the form of tablets, patches or intravenously.
But illicit forms of the drug are commonly sold as a powder or pressed into pills. Fentanyl and chemically similar variations, known as analogs, have been sold on the black market and can be extremely potent.
"This was a very serious incident and it involved a lot of people but I'm telling you, it could have been a lot worse," Dr. Kurt Tucker, a physician at Adena Regional Medical Center, said.
Tucker described the substance as a "very fine powder."
About 31 inmates who were not affected by the substance were removed from the cell block and moved to other areas, according to the highway patrol.
Troopers said the facility is secure and there is no threat to the public. Authorities are investigating.
The Ohio incident comes as Pennsylvania's Corrections Department said it had issued a statewide lockdown after staff members became sick over the last few weeks from an unknown substance.
Tucker called the timing "extremely coincidental."
The latest incident in Pennsylvania occurred Wednesday at Albion Correctional Facility, where five employees were sent to the hospital after processing a parole violator who was feeling sick, corrections department spokeswoman Susan McNaughton said.
Hazmat teams were called to the Albion men's prison but could not determine what the substance was, according to Albion spokeswoman Michele Tharp.
CORRECTION: A previous version of the story incorrectly described Pennsylvania's Albion state prison as a women's prison. Albion is a men's prison.