(Waukegan, IL) OSHA has announced fines against the owners of a Waukegan plant over an explosion that killed four employees earlier this year.

The 1.591-million dollars in fines against AB Specialty Silicones LLC, were said to be over what OSHA called “willful violations,” that led up to the May explosion at the plant on Sunset and Northwestern.

AB Specialty Silicones has yet to respond to the findings or the fines. The force of the blast could be felt several miles away, and caused an estimated 1-million-dollars in damages.