Authorities reported that nine workers remain missing after a chemical tank ruptured at the Nippon Dynawave Packaging facility, a pulp and paper plant located in Longview, near the Washington-Oregon border.

The incident occurred around 7:15 a.m. Tuesday and sparked a hazardous materials emergency that mobilized multiple rescue agencies.

“Our community has entered a period of profound tragedy and mourning,” Longview Mayor Erik Halvorson said during a press conference reviewed by ABC News.

The tank remains unstable

Authorities indicated that recovery efforts remain extremely complex due to the structural instability of the affected tank, which contained “white liquor,” a chemical mixture used in the paper manufacturing process.

The damaged structure, with a capacity of 900,000 gallons, would still contain about 90,000 gallons of the chemical material, composed of sodium hydroxide, sodium sulfide and sodium carbonate.

There is one death and multiple injuries

Authorities confirmed one death related to the incident. The victim had previously been taken to a hospital, although his identity has not been released.

Additionally, eight employees were injured, some with chemical burns and traumatic injuries. The patients were distributed between hospitals in the region and specialized burn centers in Portland, Oregon.

PeaceHealth St. John Medical Center reported that it received nine patients from the emergency room, including the deceased.

A firefighter was also injured during the initial response, although he was later released.

The cause of the accident remains under investigation

Authorities initially described the incident as a chemical explosion and later as an implosion, although they later clarified that it was a tank rupture.

Investigators noted that, at the same time as the collapse of the chemical warehouse occurred, a water main pipe ruptured within the facility.

According to preliminary reports, nearly 500,000 gallons of the chemical mixture were combined with water, although authorities assured that the material remains contained within the industrial site.

Washington Governor Bob Ferguson reported that members of the National Guard will collaborate in search, recovery and air quality monitoring efforts.

Although the situation remains active, authorities stated that there is no direct threat to the nearby community.

However, they asked residents to avoid the area while emergency operations and stabilization of the plant continue.

The investigation into the causes of the breakup remains open.