LONGVIEW, Wash. (AP) — The implosion of a chemical tank at a pulp and paper mill in southwestern Washington state on Tuesday injured at least 10 people, while an undisclosed number of others were killed or remained missing, authorities said.

In a joint statement, Nippon Dynawave Packaging Co. and local first response agencies confirmed there had been fatalities.

Cowlitz Fire and Rescue Chief Scott Goldstein later told a news conference that it was unclear how many workers had been killed. Asked how many remained missing, he replied: “We have information on that, but we’re not releasing that information.”

Among those injured was a responding firefighter. Authorities said some victims had suffered burns or inhalation injuries, and that the severity of the injuries ranged from minor to critical. There was no immediate threat to the public, they said.

The statement, issued more than four hours after the tank imploded at 7:15 a.m., said crews were continuing recovery operations and that no identifying information would be released about victims pending notification of relatives.

Some people waited at the company’s visitor entrance on Tuesday, seeking information about loved ones who worked at the facility. They declined to comment to an Associated Press reporter.

The Nippon Dynawave Packaging Co. facility is a pulp and paper mill and liquid packaging plant along the Columbia River in Longview, a city of about 38,000 that has had a relationship with the paper and lumber industries since its founding by a Kansas City timber baron in the 1920s.

The facility, which employs about 1,000 people, makes material for tissues, printing paper, cups, plates, cartons and other goods. It is located in an industrial zone shared by other timber, paper and chemical businesses, and it remains central to the community.

“The people who are responders here have friends and relatives that work on site,” Goldstein noted. “It is something that is impactful, and we have support networks to support the workers as well as the emergency responders.”

The 80,000-gallon (303,000-liter) tank that imploded was about 60% full, Goldstein said. It contained a chemical brew known as "white liquor,” a corrosive substance that consists mainly of sodium hydroxide and sodium sulfide and is used to break down wood to make kraft paper, a durable paper used in packaging, shopping bags and other products.

It was too early to determine the cause of the implosion, Goldstein said.

In a written statement, U.S. Sen. Patty Murray of Washington called the implosion an “absolute tragedy.”

“My heart is with everyone who lost a loved one today — as well as the injured workers,” she said.

Mike Gorsuch, battalion chief with the fire department in Longview, Washington, described it as a “mass casualty scene.” He said first responders had decontaminated patients and taken them to hospitals in Longview and Vancouver, Washington.

About 40 firefighters and paramedics had responded, along with a regional hazmat team, Gorsuch said.

Following the tank's rupture, the white liquor spilled into a drainage ditch, said Brittny Goodsell, a state Ecology Department spokesperson. The department sent a team to evaluate the impacts, Goodsell said.

Thousands of residents of Southern California remained evacuated Tuesday due to a damaged chemical tank at an aerospace plant.

Just over 40 people died between January 2021 and mid-October 2023 as a result of hazardous chemical incidents, according to a paper released by a network of environmental justice organizations in late 2023.

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Boone reported from Boise, Idaho. Associated Press reporters Gene Johnson in Seattle and Christopher L. Keller in Albuquerque, New Mexico, contributed.

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