Two people are dead and at least 20 injured following an explosion Sunday morning at a Colorado mine.

The 7.20am blast killed two people at the Ouray County mine, a further 20 were taken to local hospitals. Operator Star Mines has accounted for all other employees.

A Star Mines spokesperson told the Plain Dealer that the injuries came from workers inhaling toxic chemicals and gases immediately after a ‘powder smoke incident’ triggered the blast.

The miners are suspected to have inhaled nitrogen dioxide and carbon dioxide, the paper added.

The mine is located in southwest Colorado almost 300 miles north of Albuquerque, New Mexico.