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.