Explosion 'like thunder' rocks Pa. steel plant; 1 dead, 10 injured: Live updates

One person has been killed, one is missing and 10 were injured following an explosion Monday at a steel plant in Clairton, Pennsylvania, on the outskirts of Pittsburgh, officials said.

Allegheny County Emergency Services and the Allegheny County Police Department responded to the blast at the U.S. Steel Clairton Coke Works plant and confirmed the fatality in a social media statement.

One the two persons initially reported missing was rescued, joining the list of those injured and transported to a local hospital, according to Victor Joseph, assistant superintendent of the county police.

U.S. Steel Executive Vice President Scott Buckiso told reporters at an afternoon news conference the plant is stable except for the two structures shut down after the 10:50 a.m. explosion. An investigation into the cause has begun amid the search for the missing worker.

"It's an ongoing rescue effort for the one person that is still not accounted for,'' Buckiso said. "We think we know the general location of that employee, but we're not 100% sure.''

Construction worker Zachary Buday, who was near the steel plant when the explosion happened, told WTAE-TV in Pittsburgh that it "sounded like thunder."

"It shook my chest. It shook the building, then we saw the dark smoke rising from the steel mill," he said. "Put two and two together. It's like something bad happened.''

The moment of the blast, followed by large plumes of smoke shooting high into the air, is captured live in video from the BreatheProject, a Pittsburgh-based nonprofit that advocates for improvements to air quality in southwestern Pennsylvania.

Gov. Shapiro says 'multiple explosions' took place at plant

Pennsylvania Gov. Josh Shapiro said on social media the steel plant was the site of "multiple explosions,'' and that his administration will provide whatever resources are required.

"Injured employees have now been transported to local hospitals to receive care, and search-and-rescue efforts remain active at the plant,'' Shapiro said. "If you’re in the area, continue to follow the instructions of local authorities.''

U.S. Sen. John Fetterman of Pennsylvania said on social media he went to the plant Monday and spoke with officials, workers and members of the community.

"Search and rescue still underway, air is safe but remain inside,'' he said. "This is still an active scene.''

Residents near plant advised to stay indoors

The Allegheny County Department of Health issued a statement saying it was "actively monitoring the explosion" in coordination with first responders.

Residents within one mile of the plant were being advised "out of an abundance of caution" to remain indoors, close windows and doors and set their home cooling units to recirculation. Air quality monitors had not detected levels of toxins above federal standards, the department said. 

Two workers at steel plant injured in February fire

A fire at the plant Feb. 5 injured two workers after a buildup of gases ignited, the Allegheny Front reported.

The Allegheny County Health Department said in a statement at the time that the incident was the result of a “hydraulic failure in a switch of the batters which led to a buildup of combustible material,” which then ignited.

The statement said a “boom” was heard and emissions leaked from the facility. The workers received first aid at the plant, were taken to a local hospital and released, the Allegheny Front reported.

The Allegheny County Department of Health has a webpage that includes recent legal actions dating to 2018 against the plant, including penalties for emissions violations, leaks and process and equipment failures.

Where is U.S. Steel Clairton Coke Works?

Clairton is about 20 miles south of Pittsburgh. The Clairton Plant is the largest coke manufacturing facility in the country and serves the commercial coke market as well as U.S. Steel's steelmaking facilities, according to U.S. Steel.

The plant operates 10 coke oven batteries and annually produces more than 4 million tons of coke, a type of fuel used in the steelmaking process, per U.S. Steel.

What is a coking plant?

A coking plant turns coal into coke, which is in turn used to make steel in a blast furnace. The coal is softened, then liquified and re-solidified into coke. Coal in a coking plant is heated without oxygen to temperatures as high as 1,125 degrees Fahrenheit, removing its impurities. The resulting coke is a porous, carbon-heavy material.