ONE person has been confirmed dead and several others with critical injuries after a chemical tank imploded and ruptured in Washington, authorities say.

At least nine other people are also unaccounted for as rescue crews continue to search the Nippon Dynawave Packaging facility.

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Multiple people have died in an implosion at a Nippon Dynawave Packaging facility in Washington
 

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The number of fatalities remains unknownCredit: x.com/@komonews
There are fears the death toll could increase following the horrific ordeal, just 45 miles north of Portland, Oregon, on Tuesday.

Nine people were rushed to hospital needing treatment for chemical burns.

Emergency responders rushed to the scene, according to the Longview Fire Department and the Nippon and Cowlitz County Sheriff’s Department.

As people waited outside the company’s visitor entrance seeking information about loved ones, authorities confirmed at least one person had perished in the implosion.

In a joint statement authorities said the implosion posed “no immediate threat to the surrounding community”.

Officials confirmed there had been “fatalities related to the incident” as well as “multiple critical injuries”.

But specific figures are yet to be released.

At least nine workers and a firefighter were taken to surrounding hospitals from the site, according to Cowlitz 2 Fire & Rescue chief Scott Goldstein.

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Cowlitz 2 Fire & Rescue Chief Scott Goldstein spoke to local media on Tuesday morningCredit: AP
 

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The Nippon Dynawave Packaging Co. facility is a pulp and paper mill and liquid packaging plantCredit: Google Maps
He said the number of deaths was still “undetermined” during a press conference on Tuesday.

The PeaceHealth St. John Medical Center in Longview confirmed it had seen nine patients in relation to the implosion, including one who had died, ABC News reported.

Authorities said a tank containing “white liquor” – a chemical solution of sodium hydroxide and sodium sulphide – had ruptured at around 7.15am.

The chemical mixture is used in the production of paper pulp.

Goldstein told local reporters that the 80,000-gallon tank had been at least 60 per cent full at the time of the implosion.

“We’re dealing with life safety concerns and incident stabilisation at this point,” he said.

Mike Gorsuch, battalion chief with the Longview Fire Department, also described it as a “mass casualty scene”.

He revealed at least 40 firefighters and paramedics had responded, alongside a regional hazmat team.

U.S. Sen. Patty Murray of Washington called the implosion an absolute tragedy.

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

The Nippon Dynawave Packaging Co. facility is a pulp and paper mill and liquid packaging plant that makes material for tissues, printing paper, cups, plates, cartons and other goods.

At least 1,000 people work at the site, according to the Washington State Department of Ecology.

It is located in an industrial zone shared by other timber, paper and chemical businesses, and it remains central to the community.

The shocking implosion has come after thousands of residents in Southern California were evacuated from their homes after officials suspected a chemical tank at an aerospace facility was leaking.

Around 50,000 residents in Garden Grove have been forced from their homes after the damaged tank began venting dangerous vapors last week.

The tank at GKN Aerospace contains between 6,000 and 7,000 gallons of methyl methacrylate (MMA) – a highly flammable chemical used to make plastic aircraft parts.

Emergency crews have spent days desperately trying to cool the tank after it overheated on Thursday when a relief valve opened.