DERIDDER, Louisiana - Three men were killed and seven people were injured Wednesday morning in a violent explosion at a Louisiana containerboard mill.

The explosion happened in the pulp mill section of Packaging Corporation of America's DeRidder Containerboard Mill at about 11:10 a.m.

A 25-foot tank containing "foul condensate" exploded, killing the men, some of whom were contractors, officials said.

Of the seven injured, six suffered minor injuries and one suffered moderate injuries, according to Sgt. James Anderson of the Louisiana State Police.

One person was previously reported missing but they have since been accounted for. However, that person's condition is unknown, according to Sgt. Anderson.

Louisiana State Police, the Beauregard Sheriff's Office and OSHA are investigating the explosion.

Anderson said there was no chemical hazard.

Anyone needing information about a loved one working at the plant who has not been in contact, should go to the covered arena at the Beauregard Parish Civic Center west of the plant on U.S. 190, said the sheriff's office.

The plant was formerly owned by Boise and was acquired by PCA in 2013.