All employees were ordered to evacuate around 2:00pm, Tuesday afternoon.
Tanks containing chlorine dioxide exploded in the Northeast corner of the building.
The explosion killed 48 year old James Gibson and sent 5 others to the Marion Hospital Emergency Room with non-life threatening injuries. 3 others refused treatment on the scene.
Witnesses say they heard an explosion and saw smoke coming from the building.
The plant employs more than 1600 people in multiple shifts.
Copyright 2016 Nexstar Broadcasting, Inc. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.