Multiple fatalities have been reported after a chemical explosion occurred at a paper mill in Washington state.

First responders were at Nippon Dynawave Packaging in Longview, “following the rupture of a tank containing white liquor,” the Longview Fire Department said in a joint statement released on Facebook by local officials and the packaging company.

White liquor is a chemical used in the process to make paper from wood chips. Cowlitz Fire Chief Scott Goldstein later said at a press conference that the ruptured tank could hold 80,000 gallons, and it was roughly 60 percent full.

The explosion occurred at around 7:15 a.m. local time on Tuesday, according to officials. The cause of the blast has yet to be revealed.

The Longview Fire Department confirmed “multiple critical injuries” related to the explosion. Officials said nine workers and one firefighter were taken to local hospitals for treatment.

Multiple people had chemical burns and other injuries from the explosion, the fire department said in a previous Facebook post.

The firefighter who was injured while responding to the explosion has since been released from the hospital, Administrative Battalion Chief Mike Gorsuch with the Longview Fire Department said at Tuesday’s press conference.

There have also been multiple fatalities, according to officials, but an exact number has yet to be released. The identities of the victims have also not been made public yet.

Officials were still searching for some people who had been unaccounted for as of Tuesday afternoon.

There is “no immediate threat” to the community, the Longview Fire Department said in its joint Facebook statement. But officials have asked people to avoid the area as they work on the scene.

“Responding agencies continue coordinating closely with facility personnel and partner agencies as the investigation and recovery efforts continue,” the fire department said.

There were five fire trucks, seven ambulances and a hazmat team responded to the paper mill.

Nippon Dynawave Packaging has around 550 employees at its pulp and paper mill, according to Washington’s Department of Ecology.

The mill makes about 280,000 tons of paperboard and wood pulp each year. It also has about 450 workers at its liquid packaging plant.

It’s unclear how many people were working at the plant during the explosion.

When asked about concerns residents may have about the chemicals involved in the explosion, Chief Goldstein said, “The industrial sites here along the Columbia River are very well established and have great safety protocols.”