Updated August 11, 2025 at 4:44 PM EDT
By Kiley Koscinski, Julia Maruca / 90.5 WESA News
One person was killed, another remained missing, and still more were injured Monday after an explosion at the U.S. Steel Clairton Coke Works that Clairton city officials said could be felt at least two miles from the sprawling Mon Valley complex.
Allegheny County officials on Monday afternoon said one person died, one person remained unaccounted for, and 10 others required hospital treatment for injuries suffered in the late-morning blast at the plant along the Monongahela River, about 15 miles south of Pittsburgh. City and county officials said multiple people initially reported injuries, but not all required hospital treatment.
Initially, officials reported that two people were missing after the explosion, and emergency crews worked through the afternoon to conduct a rescue mission in search of people who may have remained trapped under rubble. Crews found one of the missing people around 2:45 p.m. and transported that person to a hospital, Allegheny County Police Assistant Superintendent Victor Joseph said.
No information was immediately available on the cause of the explosion, but investigators from the U.S. Occupational Safety and Health Administration were on the scene Monday afternoon. Joseph said his agency also had been asked by Clairton police to assist with the investigation of the explosion, which he said would be “time-consuming.”
In a late-afternoon news conference, Scott Buckiso, U.S. Steel executive vice president and chief manufacturing officer, said the explosion occurred at the plant’s coke oven batteries 13 and 14. He said workers shut down gases and utilities used in manufacturing in that area, and that the rest of the coke works is “stable” and still operating. The company, now a subsidiary of Japan-based Nippon Steel Corp., said emergency teams were immediately dispatched to the scene, but it gave no other details about the cause of the explosions, casualties or damage.
“Our hearts go out to our employees,” Buckiso said. “Safety is our No. 1 priority, every day, every shift — 365. This is a tragedy that we want to understand.”
In a statement, company CEO David Burritt said U.S. Steel is working with authorities to investigate the cause.
Allegheny Health Network said its hospitals were treating seven patients from the explosion, although it provided no details about their injuries or conditions. The University of Pittsburgh Medical Center said it was treating two patients at UPMC Mercy, the region’s only level one trauma and burn center.
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.”
Clairton resident Amy Sowers said she also felt her house shake from the explosion while she sat on her porch, less than a mile from the plant.
“I could see smoke from my driveway,” she said. “We heard ambulances and fire trucks from every direction.”
Sowers decided to leave the area after she said she smelled a faint smell in the air.
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 facility is the largest coke works plant in North America and a major employer and source of community identity in the region. Clairton Mayor Richard Lattanzi said his heart goes out to the victims of Monday’s explosions.
“The mill is such a big part of Clairton,” he said. “It’s just a sad day for Clairton.”
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.
Those groups issued statements Monday expressing sympathy for workers and the community while reiterating longstanding concerns.
The Breathe Project, a nonprofit environmental advocacy group, offered condolences over the “horrific impact of the explosion.” In a statement, the group added that there had been repeated issues at the plan in recent years, and said, “Real progress will only come when public health and community revitalization are treated as non-negotiable priorities. There have been too many years of promise-breaking and too much emphasis on short-term deflections that continue to perpetuate community health harms and workforce anxiety.”
A pair of environmental groups and the Allegheny County Health Department in 2018 sued U.S. Steel in federal court, winning a landmark settlement last year. 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.
The plant converts coal to coke, a key component in the steel-making process. To make coke, coal is baked in special ovens for hours at high temperatures to remove impurities that could otherwise weaken steel. The process creates what’s known as coke gas — made up of a lethal mix of methane, carbon dioxide and carbon monoxide.
The United Steelworkers union, whose members split on the transaction, said in a statement that it “has occupational health and safety experts and other representatives on the ground at the Clairton Works assessing the situation and aiding our members. While we are still determining the scope of the tragedy, we are aware that multiple workers are receiving medical treatment for their injuries.” It pledged to “work with the appropriate authorities to ensure a thorough investigation and to see that our members get the support they need.”
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.”
U.S. Sen. John Fetterman, who lives in nearby Braddock, spoke with reporters gathered outside the plant after he entered the complex and spoke with some workers inside.
“Everyone’s grim. Not surprisingly — you can’t shut the facility down. It’s like a big, gigantic ship in the middle of the ocean — you can’t shut it down,” he said. “They still have to work … Everyone knows what happened. Obviously, it’s very grim there.”
Other elected officials also expressed sympathy and concern.
“My heart is with the workers, especially those injured or trapped, their families, first responders, USW members and the entire Clairton community,” said U.S. Rep. Summer Lee, whose district includes the facility. “My office remains committed to ensuring that every affected worker and family receives the support and resources they need.”
Cindi Lash of 90.5 WESA, Julie Grant of The Allegheny Front and The Associated Press contributed.
This is a developing story and will be updated.
