Authorities say preliminary autopsy results have failed to shed more light on how a worker died underground in a Montana precious metals mine.

No foul play is suspected.

Federal mine safety regulators said Thursday that a closure order remained in effect in the area of the Stillwater platinum and palladium mine where 45-year-old Mike Rued died.

Amy Louviere with the federal Mine Safety and Health Administration says the rest of the mine near Nye has been released from the order.

Rued was found unresponsive in the Stillwater Mining Co. mine late Tuesday.

Stillwater County Undersheriff Charles "Chip" Kem says the cause of death could not be determined based on initial autopsy results. Kem says it could take several weeks for the results of toxicological tests to come back.