Investigators are trying to determine how a contractor fell into a coal ash pond and died Thursday at a Kentucky Utilities power plant in Ghent, Kentucky.

According to news sources, the man was a KU contractor employed by Tetra Tech, an engineering consulting firm based in California.

Although a spokesperson for KU said the man “slipped” into the pond around noon, his body was not recovered by emergency responders until much later in the day, said Carroll County Coroner David Wilhoite.

An ash pond is an engineered structure for the disposal of bottom ash and fly ash.

The incident is under investigation.

On its website, the company says: “Safety is the foundation for all we do at LG&E and KU. We offer safety tips and information to ensure you, your family members and friends, our employees and business partners remain safe each and every day.”