TOWSON, Md. (AP) — The Maryland Department of Public Safety and Correctional Services has temporarily suspended visits at correctional institutions in response to prison staffers in other states needing treatment.

A department statement on Wednesday said there will be no prison visits until further notice. Also, mail will be accepted at prison but not opened or distributed. Prison staffers have been advised to use all provided protective equipment.

In Pennsylvania, state prisons were on a lockdown after 29 employees at 10 prisons required treatment in recent weeks from exposure to a yet-unidentified substance described in some cases as a liquid synthetic drug.

Prison guards, nurses and inmates were among the nearly 30 people in Ohio treated for possible drug exposure inside Ross Correctional Institution.

So far, no incidents have been reported Maryland.