Updated August 11, 2025 at 2:29 PM EDT
One person was killed, two others were missing, and still more were injured Monday morning after an explosion at the U.S. Steel Clairton Coke Works that city officials said could be felt at least two miles away, and a rescue operation was underway to rescue trapped workers at the sprawling Mon Valley complex.
Allegheny County officials confirmed that one person died, two people remained unaccounted for, and "multiple" others were injured after the late-morning blast at the plant along the Monongahela River, about 15 miles south of Pittsburgh. Clairton city officials said at least a dozen injuries were initially reported after the late-morning blast, and medical helicopters could be seen arriving at and leaving from the plant.
According to a county spokesperson, emergency crews at midday were conducting a rescue mission in search of people who may remain trapped under rubble.
"This remains an active incident, and the public is urged to avoid the area," county officials said in an early-afternoon statement.
Authorities said a fire was reported at the plant around 10:51 a.m. A plant worker who asked not to be identified said he was working at 10:45 a.m. when he felt the impact of the explosion, between a quarter-mile and half-mile away from his location. The worker said his friend and fellow worker was in the lunchroom at the time and got "banged up" when the explosion knocked him out of his chair.
John LaBarbara, who said he worked at the coke works until a week ago, said his father and brother were at work in the plant when the blast occurred, but they were not injured. His father has been part of the maintenance team for 30 years and works in a building where compressors are repaired; his brother works on the other side of the plant.
"They were waiting on [LaBarbara's father] to get in the truck, load up and go down," LaBarbara said, "and then he said that's when it exploded ... when they were all getting in the truck to head over there."
A dark cloud of smoke could be seen over the plant after the explosion, but little information was immediately available about the impact on air quality. The county health department said it is "actively monitoring" the aftermath of the explosion and advised people who live within a mile of the plant to stay inside, although it said it has not detected particulate matter or sulfur dioxide — components of air pollution that can cause health risks — above federal standards in the air.
The Clairton plant is the largest coke works in North America. Coke is used in a blast furnace to process iron ore into steel. It is made by heating coal to high temperatures, and the subsequent emissions are classified as carcinogens. The plant is by far the largest source of benzene and other pollutants in Allegheny County.
The site has drawn ire from public health and environmental advocates, who routinely raise concerns about pollution emitted from the facility that negatively impacts the region's air quality. Following a catastrophic 2018 fire that destroyed pollution controls, asthma exacerbations rose among residents within 10 miles of the plant.
A pair of environmental groups and the Allegheny County Health Department sued U.S. Steel in federal court and won a landmark settlement. The settlement required the closure of one of the plant's coke batteries, as well as $19.5 million in upgrades to its coke oven gas cleaning facilities. The agreement also included $4.5 million for local communities impacted by the 2018 fire.
Combined with $17.5 million in upgrades the plant had undertaken since the federal lawsuit was filed, the total settlement of $42 million was the largest Clean Air Act citizen's suit ever in Pennsylvania, according to the National Environmental Law Center, which represented environmental groups in the suit.
The coke works is among the region's U.S. Steel facilities now owned by Japan-based Nippon Steel following a historic partnership agreement between the two companies. The combined company is the fourth-largest steelmaker in the world.
Nippon committed to investing $11 billion to upgrade U.S. Steel facilities in June. A spokesperson for Nippon did not immediately respond to a request for comment about Monday's explosion.
In a statement, Gov. Josh Shapiro said the state Emergency Management Agency and state police have offered "all assistance" to emergency responders at the plant and in the Mon Valley.
"The scene is still active, and folks nearby should follow the direction of local authorities," the governor said. "Please join Lori and me in praying for the Clairton community."
Cindi Lash of 90.5 WESA and Julie Grant of The Allegheny Front contributed.
This is a developing story and will be updated.
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