The death toll from the tank-rupture incident at a Washington state paper mill on Tuesday rose to two, with nine people still missing and presumed dead, authorities said.

The Longview fire department said in a statement on Wednesday afternoon that one person who was transported to the hospital following the disaster at Nippon Dynawave Packaging Co on Tuesday morning had died.

“We’re bracing ourselves for this being the deadliest industrial tragedy in modern Washington state history,” Washington governor Bob Ferguson said at a news conference with local authorities on Wednesday.

The agency said that recovery efforts began at the mill on Wednesday following a delay due to “safety concerns of the structural integrity of the damaged tank”. Authorities have said there is no hope of finding any additional survivors and that the operation had transitioned from rescue to recovery.

Meanwhile, a team of investigators with the US Chemical Safety and Hazard Investigation Board (CSB) was set to arrive on scene Wednesday after the federal agency announced it was launching an investigation into the fatal implosion.

The incident began when an industrial tank ruptured and released white liquor, a highly destructive chemical mixture used in the paper industry. In the initial aftermath, officials confirmed one death and nine injuries, including a firefighter who had responded to the scene. Seven workers remain hospitalized.

Matt Amos with the Longview fire department said operations would be “slow, methodical and deliberate” and that recovered victims would undergo decontamination before being transported to the coroner. Crews are searching the area in chemical protective equipment.

“The priority is ensuring responder safety while treating every victim with the greatest dignity, care and respect as possible,” Amos said.

While the cause remained unknown, authorities in Longview said there was no threat to the Columbia River community, a city of about 40,000 people with long ties to the Washington and Oregon paper and lumber industries.

It was the second notable chemical tank failure in days on the west coast, following the evacuation of thousands of southern California residents due to a damaged tank at an aerospace plant.

The sprawling Longview plant, which employs about 1,000 people, makes material for tissues, printing paper, cups, plates and cartons. The facility sits right along the river next to other timber, paper and chemical businesses.

The paper mill tank was holding about 600,000 gallons of a liquid made of mostly sodium hydroxide and sodium sulfide. Known as “white liquor”, it is used with heat to break down wood to make kraft paper, a durable material used in packaging, shopping bags and other products. The tank still has some 25,000 gallons of the liquid, which is slowly leaking, officials said.

Following the tank’s rupture, the liquid spilled into a drainage ditch, said Brittny Goodsell, a state ecology department spokesperson.

Sampling revealed that contamination had entered the river on Tuesday, officials said, and dead carp were found. They urged the public to avoid ditches and dikes while the area undergoes water testing, but said there were no issues related to air quality or drinking water in Longview.

The Washington state department of ecology and the US Environmental Protection Agency are overseeing operations to determine any environmental impacts related to the incident, the fire department said.

At a community vigil on Tuesday night, dozens of people gathered to pray, light candles and embrace loved ones.

Crystal Moldenhauer, a Longview resident, said she had friends at the plant who remained unaccounted for. She said people had called and texted each other all day trying to figure out what happened.

“We’re all still waiting for answers,” she said. “There’s families that have been torn apart, and we don’t know why.”

Safety complaints were filed against Nippon Dynawave in March and May. The state’s labor and industries department said on X that both were unrelated to the current situation. One was an anonymous complaint about a valve on a tank, according to the department, which noted that it was not the tank that imploded.

Nippon Dynawave, a subsidiary of Japan-based Nippon Paper Group, has been fined $3,400 for three separate health and safety violations found by Washington department of labor and industries inspectors since the start of 2021, according to the department’s online database.

Brian Wood with Nippon Dynawave said during a news conference on Wednesday that the company was focused on the victims and helping first responders recover the missing.

“These are our people,” he said.

He said Nippon Dynawave would “cooperate to the maximum extent” with the investigation and that “it is our duty and our obligation to do so”.

Forty-three people died from January 2021 to mid-October 2023 as a result of hazardous chemical incidents in the US, according to a paper released by a network of environmental justice organizations in late 2023.