The implosion of a chemical tank at a Washington packaging plant early on Tuesday morning killed at least one person and left at least nine others with injuries including chemical burns, authorities said.

The Longview fire department confirmed one fatality at Nippon Dynawave Packaging in a statement on their social media page. It also confirmed eight employees were injured and one firefighter. Nine people who are employees of the plant remain unaccounted for, officials said.

According to the fire department, the chemical incident occurred when a tank containing white liquor, a chemical solution used in the paper industry, ruptured. According to the state, the plant has a kraft pulp and paper mill and liquid packaging facility, and employs roughly 1,000 employees.

In a joint statement from the fire department, Nippon Dynawave Packaging and local agencies, officials said late on Tuesday morning that there were “fatalities related to the incident”.

“The scene remains in the recovery phase as emergency responders continue operations. No identifying information regarding injured or deceased individuals will be released at this time pending notification of family members,” authorities said.

Michael Gorsuch, battalion chief of the Longview fire department, told KGW 8 earlier on Tuesday that some injuries were critical and most were life-threatening.

Gorsuch said during the news conference that there were also people who remained unaccounted for.

There is “no immediate threat to the public”, the fire department said, but people should avoid the area.

The department said crews were continuing to work with Nippon employees “to mitigate the product and container involved”.

In a written statement, Patty Murray, a US senator 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.

The tank, which was used to store caustic white liquor, was roughly 60% full at the time of the rupture, said the fire chief, Scott Goldstein. White liquor is an alkaline solution used to break solid wood chips into pulp in the paper-making process and is made up mostly of sodium sulfide, sodium hydroxide and disodium carbonate.

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. However, officials said there was no direct threat to the surrounding community.

Nippon Dynawave Packaging did not immediately respond to inquiries from the Guardian.

The Nippon Dynawave Packaging 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 and dates back to 1953, 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,” Scott Goldstein, the Cowlitz fire and rescue chief, noted. “It is something that is impactful, and we have support networks to support the workers as well as the emergency responders.”

The Washington incident comes after authorities in southern California ordered the evacuation of about 50,000 people in Garden Grove last week over fears a damaged chemical tank might explode. Orange county officials said on Monday that the threat of a major explosion had been eliminated and began lifting evacuation orders.

But officials have said there is still a threat to public safety and crews continue to work to mitigate the remaining risks.

Associated Press contributed reporting