At least two killed in Colorado silver mine accident DENVER (Reuters) - Two miners were killed and 20 injured on Sunday in an accident at a silver mine in southwestern Colorado, authorities said. The cause of the accident at the historic Revenue-Virginius Mine in Ouray County, about 330 miles southwest of Denver, was under investigation, according to county spokeswoman Marti Whitmore. She said authorities had ruled out an explosion or cave-in, however. The mine is owned by Denver-based Star Mine Operations, LLC but company officials could not be reached for immediate comment. Of the 20 miners injured in the accident, Whitmore said one remained in critical condition late on Sunday at a hospital. The Revenue-Virginius mine was first staked in the 19th century and was just re-opened this year after years of inactivity, according the Ouray Historical Society. It is located at an elevation of 12,000 feet along the so-called Governor Basin in the rugged San Juan Mountains. Reporting by Keith Coffman; Editing by Bill Trott