The Star Mining Company in Denver, owner of the mine, couldn't be reached for comment.
The Watch reported that "mine manager Rory Williams of the Star Mining Company said the injuries were a result of miners breathing in gases and chemicals in the air following a blast."
A rescue party reached the bodies of two miners at about 3 p.m., and the Ouray County Coroner declared them dead when they were brought to the surface, Whitmore said.
"There were two miners who didn't get out on their own, and the rescue operation was to retrieve them. When they were brought out they were declared fatalities," she said.
"We don't know if they are alive," she had said earlier in the day. " We know that it is not like there was a cave-in and they are behind rocks," Whitmore said.
Star Mining has accounted for all personnel who were at the site.
The federal Mine Safety and Health Administration is at the site.
At least 14 were affected by gases in the explosion, nitrogen dioxide and carbon dioxide, according to the Watch.
The critically injured miner was taken to Montrose Memorial Hospital. An additional nine people were transported by ambulance to Montrose Memorial. Five people were transported to Delta Memorial Hospital, and five people were taken to St. Mary's Hospital in Grand Junction.
The previous mining fatality in Colorado happened June 14, 2012, when 25-year-old Jason Kawcak when the water truck he was driving overturned at the Colowyo Mine in Moffat County, according to the U.S. Department of Labor.
Before the Revenue-Virginius disaster, there were 34 fatalities at mines in 2013 in the United States, according to the federal Department of Labor. There have been 15 mining deaths in Colorado in the past decade, according to the department's Mine Safety and Health Administration.
This story will be updated as more information becomes available.