With family members looking on, rescue crews pulled out on stretchers the bodies of three miners found near the entrance to one of two tunnels where the miners are believed trapped.
The morning explosion in the remote hamlet of San Roque, 410km northeast of Bogota, was caused by "some spark and the gas that was inside" the mine, Rosales said.
Norte de Santander, where the mine is located, is one of Colombia's most violent-stricken states, an area overrun by leftist guerrillas and right-wing paramilitary groups who often battle each other for control of lucrative drug smuggling routes across the border with Venezuela.
Many mines in this Andean nation are makeshift affairs with few or no safety procedures.
In January 2006, three self-employed coal miners - a 60-year-old father and his two sons - died at a mine in the same region after inhaling poisonous gases.
Other mine disasters in Colombia have been the result of landslides and erosion. In 2001, at least 37 gold miners were killed after a hillside gave way and swept over them at a strip mine located 200km west of Bogota.
The mine had been shut down earlier in the year because erosion made it unstable.