MCCOOK, Neb. (AP) — Two McCook city employees have been found dead inside a wastewater treatment plant.

The Kearney Hub reports that the bodies of 65-year-old Larry Dicke and 43-year-old Kenneth Keslin were found Sunday afternoon inside a sludge pumphouse at the McCook plant.

Police said in a news release that officers were sent to the plant for a welfare check after one of the employees failed to return home from work.

Officers spotted an employees’ personal items outside of the pumphouse, prompting a search inside and the discovery of the bodies.

Police have not said how the men died, but noted a hazardous materials team was sent in to retrieve the bodies because of toxic gases inside.