(AP) — Authorities are investigating the death of a worker at Cooper nuclear power plant in southeast Nebraska, but foul play isn’t suspected initially.

The Nebraska Public Power District says the contract worker was found dead in Cooper’s reactor building between 7:30 and 8 Tuesday morning. The utility says natural causes are suspected in the death.

The plant’s paramedics tried to help the worker who was employed by a contractor doing work at Cooper, which is near Brownville and about 80 miles south of Omaha.

The worker’s name wasn’t immediately released. The Nemaha County Sheriff is investigating the death.

NPPD officials say they notified the Nuclear Regulatory Commission and Occupational Safety and Health Administration about the death.

NRC spokeswoman Lara Uselding says her agency will monitor the investigation.