The incident occurred on Tuesday at the Nippon Dynawave Packaging plant in Longview, where a massive storage tank containing a highly caustic industrial chemical ruptured during an early morning shift change, triggering a large-scale emergency response and search operation.

“We have recovered the ninth and final missing employee of this incident,” Longview Fire Department Chief Brad Hannig told reporters, confirming the end of the recovery effort.

Authorities had earlier reported two fatalities immediately following the accident, while nine workers remained unaccounted for amid difficult search conditions inside the industrial complex.

According to officials, the accident involved a 900,000-gallon tank holding a substantial quantity of white liquor, a chemical solution widely used in paper production. The tank ruptured after what authorities described as an implosion, releasing large volumes of the substance within the facility.

White liquor is a highly alkaline mixture containing sodium hydroxide and sodium sulfide. In the pulp and paper industry, it is used to break down wood chips into pulp, a key step in paper manufacturing.

The scale of the tank and the hazardous nature of the chemical complicated rescue and recovery efforts throughout the week, prompting a major response from local emergency services.

The facility is operated by Nippon Dynawave Packaging, a U.S.-based subsidiary of Japan’s Nippon Paper Group. According to company information, the plant manufactures paper-based packaging products and produces approximately eight billion single-serve containers annually for customers across North America, Asia and other international markets.

Authorities have not yet released details regarding the cause of the tank failure. Investigations into the incident are expected to examine operational procedures, equipment integrity and workplace safety conditions at the facility.

The accident ranks among the deadliest industrial incidents in Washington state in recent years and is likely to intensify scrutiny of chemical storage and safety practices within the pulp and paper manufacturing sector.

The incident occurred at an aerospace facility in Garden Grove, southeast of Los Angeles, where a storage tank holding about 7,000 gallons (26,000 liters) of methyl methacrylate developed a leak. Emergency officials warned that the situation posed significant risks to nearby communities due to the chemical’s flammable nature and the possibility of a thermal runaway reaction.

Incident Commander Craig Covey said emergency planners were preparing for two primary scenarios: a complete tank failure resulting in a large chemical spill or an explosion that could affect neighboring tanks containing fuel and other hazardous materials.

“We are setting up these evacuations in preparation for these two options,” Covey said, describing the threat as serious and requiring immediate precautionary measures.

Garden Grove Police Chief Amir El-Farra said approximately 40,000 people were covered by the evacuation order, although several thousand residents chose to remain in their homes despite warnings from authorities.

Emergency crews continuously sprayed water on the tank in an effort to reduce its temperature and stabilize conditions. Later on Friday, Covey reported that cooling operations had succeeded in lowering the tank’s temperature to about 61 degrees, closer to what officials described as a safe operating range.

Authorities continued searching for alternatives that could further reduce the risk of either a major spill or an explosion.

Orange County Health Officer Regina Chinsio Kwong said the evacuation zone was established to protect residents from potential exposure to hazardous vapors in the event of a catastrophic failure.

She urged the public to report any detection of a strong fruity odor associated with methyl methacrylate, while noting that the smell alone did not necessarily indicate harmful exposure levels.

No injuries had been reported as of Friday evening, and officials had not determined the cause of the leak, which was first identified on Thursday.

Emergency responders were also preparing containment measures to prevent any released chemical from entering storm drains, waterways or channels that flow into the Pacific Ocean.

According to the U.S. Environmental Protection Agency, methyl methacrylate can irritate the skin, eyes and respiratory system. Acute or prolonged exposure may also result in respiratory and neurological effects.