A mining accident Sunday morning in Colorado injured 20 and killed two people. According to the Colorado Mine Safety and Health Administration, gases were released after an incident involving explosives occurred at a mine seven miles south of Ouray at the Revenue-Virginius mine.

A foreman and one miner were overtaken with gases after the incident and trapped underground. The two fatalities were confirmed that afternoon and were identified by county officials to be Nick Cappanno and Rick Williams. Cappanno was 34 and Williams was 59. They were both from Durango. Other miners in that area were evacuated just before 8:00 that morning.

During the mine’s golden-age between 1876 and the late 1940s, the Revenue-Virginius mine produced over 14.5 million ounces of silver. That would be enough to withstand the 1893 Silver Panic. Star Mine Operations, LCC, the owner of the mine, acquired the property in late 2011.

Rory Williams, the project manager for Star Mine Operations, told the Ouray Watch newspaper that the accident was a “powder-smoke incident,” and was unrelated to a mine collapse or cave-in. He said that the miners were injured because of the release of chemicals in the smoke. The project manager also told the Associated Press that all miners were required to wear personal respirators, including the two that died. Rick Williams and Cappanno both had the respirators, and Williams said it does not appear the equipment malfunctioned.