An explosion at a US Steel plant in Pennsylvania has killed 2. Here's what to know

An explosion at a U.S. Steel plant south of Pittsburgh killed two people and injured more than 10 others. The CEO has vowed to find out what caused Monday's blast while the workers' union says it will make sure there's a thorough investigation.

The plant, Clairton Coke Works, is one of four major plants in Pennsylvania owned by U.S. Steel, an icon of the domestic steel industry and American industrialization. The company is now a subsidiary of Japan’s largest steelmaker, Nippon Steel, after a nearly $15 billion deal was finalized in June. The combined company is the world’s fourth-largest steelmaker in an industry dominated by China.

Democratic Gov. Josh Shapiro and plant executives vowed Tuesday to do whatever is necessary to prevent it from happening again.

“We owe them an answer for what happened,” Shapiro said of the workers. “We owe them the answers to their questions, and we owe them to never forget the sacrifices that occurred here yesterday.” Before arriving at a news conference, he met with family members of a worker who died.

Here's what to know about the explosion:

Allegheny County Emergency Services said a fire at the plant started around 10:50 a.m. Two loud booms that followed were initially thought to be subsequent explosions, but U.S. Steel’s chief manufacturing officer, Scott Buckiso, said those noises came from the activation of two relief pressure valves — a safety mechanism that operated as expected.

The blast could be felt in the nearby community in the Mon Valley, a region synonymous with steel in Pennsylvania, and county officials warned residents to stay away from the scene so emergency crews could respond.

One worker was rescued from the smoldering rubble hours later. Hospital officials have not released his condition as of Tuesday afternoon.

The Allegheny County Police Department said five people were hospitalized in critical but stable condition Monday night, and five others had been treated and released. Multiple individuals were treated for injuries at the scene, but the department said it did not have an exact number.

The plant converts coal to coke, a key component in the steel-making process. It’s the largest coking operation in North America and employs 1,400 workers.

Coke is made by baking coal in special ovens for hours at high temperatures, which removes impurities that could otherwise weaken steel. The process creates what’s known as coke gas — a lethal mix of methane, carbon dioxide and carbon monoxide.

Clairton Coke Works has had other explosions and fatal accidents:

After Monday's blast, the county health department initially told residents within 1 mile (1.6 kilometers) of the plant to remain indoors and close all windows and doors. The department lifted the advisory after its monitors didn’t detect levels of soot or sulfur dioxide above federal standards.

In 2018, a Christmas Eve fire damaged pollution control equipment and led to repeated releases of sulfur dioxide, according to a subsequent lawsuit. The fire prompted Allegheny County to warn residents to limit outdoor activities. Residents said it was hard to breathe for weeks afterward and that the air felt acidic and smelled like rotten eggs. U.S. Steel settled the lawsuit last year with an agreement to spend $19.5 million in equipment upgrades and $5 million on local clean air efforts and programs.

Dr. Deborah Gentile, the medical director of Community Partners in Asthma Care, studied asthma levels after the fire and found twice as many patients sought medical treatment.

In 2019, U.S. Steel agreed to settle a lawsuit regarding air pollution from Clairton for $8.5 million.

Founded in 1901 by J.P. Morgan, Andrew Carnegie and others, U.S. Steel has been an icon of the American steel industry that dominated the world market until Japan, then China, became preeminent steelmakers over the past 40 years.

Its steel has helped build everything from the United Nations headquarters in New York City to the New Orleans Superdome.

The acquisition by Nippon Steel took more than a year to come together after U.S. Steel shareholders approved it, as the parties surmounted obstacles created by national security concerns and presidential politics in a premier battleground state.

The deal includes what is known as a “golden share” provision that gives the U.S. government the power to appoint a board member and a say in company decisions that affect domestic steel production and competition with overseas producers. The combined company is the world’s fourth-largest steelmaker in an industry now dominated by China.

Pennsylvania Governor Josh Shapiro talks with media at the Clairton Coke Works, a U.S. Steel plant, in Clairton, Pa., Tuesday, Aug. 12, 2025. (AP Photo/Gene J. Puskar)

The Clairton Coke Works, a U.S. Steel coking plant, is seen Monday, Aug 11, 2025, in Clairton, Penn. (AP Photo/Gene Puskar)

The Clairton Coke Works, a U.S. Steel coking plant, is seen Tuesday, Aug 12, 2025, in Clairton, Penn. (Sean Stipp/Pittsburgh Tribune-Review via AP)

The Clairton Coke Works, a U.S. Steel coking plant, is seen Monday, Aug 11, 2025, in Clairton, Penn. (AP Photo/Gene Puskar)

The Clairton Coke Works, a U.S. Steel coking plant, is seen Monday, Aug 11, 2025, in Clairton, Penn. (AP Photo/Gene Puskar)

Ambulances are seen after an explosion at the Clairton Coke Works, a U.S. Steel coking plant, Monday, Aug 11, 2025, in Clairton, Penn. (AP Photo/Gene Puskar)

The Clairton Coke Works, a U.S. Steel coking plant, is seen Monday, Aug 11, 2025, in Clairton, Penn. (AP Photo/Gene Puskar)

The Pentagon said Thursday that it is changing the independent military newspaper Stars and Stripes so it concentrates on “reporting for our warfighters” and no longer includes “woke distractions.”

That message, in a social media post from Defense Secretary Pete Hegseth's spokesman, is short on specifics and does not mention the news outlet's legacy of independence from government and military leadership. It comes a day after The Washington Post reported that applicants for jobs at Stars and Stripes were being asked what they would do to support President Donald Trump's policies.

Stars and Stripes traces its lineage to the Civil War and has reported news about the military either in its newspaper or online steadily since World War II, largely to an audience of service members stationed overseas. Roughly half of its budget comes from the Pentagon and its staff members are considered Defense Department employees.

The outlet's mission statement emphasizes that it is “editorially independent of interference from outside its own editorial chain-of-command” and that it is unique among news organizations tied to the Defense Department in being “governed by the principles of the First Amendment.”

Congress established that independence in the 1990s after instances of military leadership getting involved in editorial decisions. During Trump's first term in 2020, Defense Secretary Mark Esper tried to eliminate government funding for Stars and Stripes — to effectively shut it down — before he was overruled by the president.

Hegseth's spokesman, Sean Parnell, said on X Thursday that the Pentagon “is returning Stars and Stripes to its original mission: reporting for our warfighters.” He said the department will “refocus its content away from woke distractions.”

“Stars and Stripes will be custom tailored to our warfighters,” Parnell wrote. “It will focus on warfighting, weapons systems, fitness, lethality, survivability and ALL THINGS MILITARY. No more repurposed DC gossip columns; no more Associated Press reprints.”

Parnell did not return a message seeking details. The Daily Wire reported, after speaking a Pentagon spokeswoman, that the plan is to have all Stars and Stripes content written by active-duty service members. Currently, Congress has mandated that the publication's publisher and top editor be civilians, said Max Lederer, its publisher.

The Pentagon also said that half of the outlet's content would be generated by the Defense Department, and that it would no longer publish material from The Associated Press or Reuters news services.

Also Thursday, the Pentagon issued a statement in the Federal Register that it would eliminate some 1990s era directives that governed how Stars and Stripes operates. Lederer said it's not clear what that would mean for the outlet's operations, or whether the Defense Department has the authority to do so without congressional authorization.

The publisher said he believes that Stars and Stripes is valued by the military community precisely because of its independence as a news organization. He said no one at the Pentagon has communicated to him what it wants from Stars and Stripes; he first learned of its intentions from reading Parnell's social media post.

“This will either destroy the value of the organization or significantly reduce its value,” Lederer said.

Jacqueline Smith, the outlet's ombudsman, said Stars and Stripes reports on matters important to service members and their families — not just weapons systems or war strategy — and she's detected nothing “woke” about its reporting.

“I think it's very important that Stars and Stripes maintains its editorial independence, which is the basis of its credibility,” Smith said. A longtime newspaper editor in Connecticut, Smith's role was created by Congress three decades ago and she reports to the House Armed Services Committee.

It's the latest move by the Trump administration to impose restrictions on journalists. Most reporters from legacy news outlets have left the Pentagon rather than to agree to new rules imposed by Hegseth that they feel would give him too much control over what they report and write. The New York Times has sued to overturn the regulations.

Trump has also sought to shut down government-funded outlets like Voice of America and Radio Free Europe/Radio Liberty that report independent news about the world in countries overseas.

Also this week, the administration raided the home of a Washington Post journalist as part of an investigation into a contractor accused of stealing government secrets, a move many journalists interpreted as a form of intimidation.

The Post reported that applicants to Stars and Stripes were being asked how they would advance Trump's executive orders and policy priorities in the role. They were asked to identify one or two orders or initiatives that were significant to them. That raised questions about whether it was appropriate for a journalist to be given what is, in effect, a loyalty test.

Smith said it was the government's Office of Personnel Management — not the newspaper — that was responsible for the question on job applications and said it was consistent with what was being asked of applicants for other government jobs.

But she said it was not something that should be asked of journalists. “The loyalty is to the truth, not the administration,” she said.

David Bauder writes about the intersection of media and entertainment for the AP. Follow him at http://x.com/dbauder and https://bsky.app/profile/dbauder.bsky.social.

US soldier Sgt. John Hubbuch of Versailles, Ky., one of the members of NATO led-peacekeeping forces in Bosnia reads Stars and Stripes newspaper on Sunday Feb. 14, 1999. (AP Photo/Amel Emric, File)

Defense Secretary Pete Hegseth stands outside the Pentagon during a welcome ceremony for Japanese Defense Minister Shinjirō Koizumi at the Pentagon, Thursday, Jan. 15, 2026 in Washington. (AP Photo/Kevin Wolf/)

FILE - A GI with the U.S. 25th division reads Stars and Stripes newspaper at Cu Chi, South Vietnam on Sept. 10, 1969. (AP Photo/Mark Godfrey)