Staff members at Butler County Prison who were sickened by an unknown substance on Tuesday are back at work, but they report that they remain sluggish, tired and dehydrated.

Warden Joe DeMore said on Thursday that he has ordered special masks to be worn by correctional officers when they perform searches.

A cell search on Tuesday sent four correctional officers and two nurses to the emergency room at Butler Memorial Hospital, after they began feeling dizzy and ill.

DeMore suspects synthetic marijuana, also known as K2 or spice, was the culprit in the event, which caused a “mass casualty” alert at the hospital.

“We have some information that that's what it was supposed to be, but we can't verify it until the tests come back,” DeMore said.

He confirmed that while prison officials are eagerly awaiting results from the tests on the substance, many times synthetic marijuana does not show up on tests. So DeMore might never know for certain what exactly sickened the workers, he said.

The masks ordered by DeMore would prevent them from being sickened by synthetic marijuana and other materials during cell searches because the product protects wearers from liquid and airborne particle contamination.

The cost for the new masks are included in the budget, DeMore said.

He said if the culprit for Tuesday's event was synthetic marijuana, there are various ways it could have made its way into the jail.

He said the most likely method was through the mail, but it could have been smuggled in by anyone.

The Westmoreland County Prison recently adjusted its mail policy to prevent illegal substances from entering the facility, DeMore said.

Cases of substance poisoning have occurred at the state correctional institutions in Mercer, Allegheny, Greene and Fayette counties in addition to many others, DeMore said.

“It could be a jail with 30 inmates and there's going to be stuff coming in,” he said.

Drug-sniffing dogs searched the entire Butler County facility on Wednesday as a result of the sickened officers and nurses, but detected nothing.