SHIPPINGPORT, Pa. -- Authorities say two workers were killed and four others were injured after inhaling toxic fumes at a Pennsylvania power plant.

Enerfab Corp. chief executive officer Scott Anderson says two employees were discharged from the hospital Friday. He says a 43-year-old worker still hospitalized "continues to show signs of improvement." There was no word on the status of a fourth injured worker.

Police said the contractors were in a "confined, well-type" area at the Bruce Mansfield Power Station in Beaver County when hydrogen sulfide gas was released early Wednesday. Police said 34-year-old Kevin Bachner and 42-year-old John Gorchock were unable to reach safety and were killed.



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Pennsylvania State Police said the workers removed an elbow joint from a pipe, releasing hydrogen sulfide gas, CBS Pittsburgh reports.

An image of the Bruce Mansfield Power Station in Shippingport, Pennsylvania. CBS Pittsburgh

"The line was not supposed to be charged, obviously. They got to the last bolt to crack it open and when they did so, this nauseous gas, hydrogen sulfide-type mixture immediately incapacitates you," State Police Lt. Eric Hermick said.

State police say first responders did all they could to rescue the men that were trapped, but it was too late.

"It's probably second-worst type of situation to respond to because you want to help somebody that's in a life-threatening situation," Hermick explained.

The accident at FirstEnergy's largest coal-fired plant in Shippingport, about 35 miles northwest of Pittsburgh, remains under investigation.