DERIDDER- Three have been killed in an explosion at Packaging Corporation of America in Beauregard Parish.

Seven others were injured as a result. Another person was declared missing following the explosion but was found around 2:50 p.m. Wednesday.

Emergency crews were called to Packaging Corporation of America, on US 190 West, just after 11 a.m. Wednesday morning.

According to Beauregard Parish Sheriff’s Office Chief Deputy Joe Toler, two tanks at the facility exploded. Investigators at the scene are still working to determine what chemical the tanks contained.

Toler says it’s unclear what caused the explosion.

According to Beauregard Regional Airport, an air medic helicopter landed near the scene.