Two miners were killed and 20 others injured in a mining accident in Ouray County, Colo., state emergency officials said Sunday.
Officials first received a call about the incident at Star Mine Operations at 7:20 a.m. Sunday, at which point 20 miners were taken to local hospitals with injuries.
Two miners remained below ground and were discovered dead, according to the Colorado Office of Emergency Management.
Rory Williams, project manager for Star Mining Operations, told the Ouray Watch that the accident was not a cave-in or a collapse but rather a "powder-smoke incident" that involved the release of chemicals.
The Watch reported that the company mines silver at the site.
Marti Whitmore, a spokeswoman for the Colorado Office of Emergency Management, told The Times that she didn't know what triggered the accident or the nature of the miners' injuries.
“We do not have information about what happened," she said. "There’s rumors flying around, but it’s all speculation."
Whitmore said that two miners remained hospitalized late Sunday afternoon and that federal mining regulators were on site after the incident.
A news conference was expected later Sunday night.
Mining fatalities have been on the decline for more than three decades, according to the federal Mine Safety and Health Administration, topping out at more than 250 deaths a year in the late 1970s.
The United States averaged about 46 such deaths a year from 2008 to 2012. This year, 27 miners had been killed through Sept. 30.