SAN FRANCISCO -- Multiple injuries were reported Tuesday morning after fire authorities announced a "major chemical explosion" at a facility in Longview, the US state of Washington.

The Longview Fire Department said in an emergency alert posted on social media that it is responding to the incident at Nippon Dynawave Packaging Company and urged residents to avoid the area.

The facility is located near the Washington-Oregon border along the Columbia River. According to the Washington State Department of Ecology, it is a kraft pulp and paper mill and a liquid packaging plant.

Authorities have not released the exact number of injuries or the cause of the explosion. According to Nippon Dynawave, its Longview facility has been manufacturing liquid packaging board since 1953 and is a subsidiary of Nippon Paper Group.