La Preciosa mine is located in the remote hamlet of San Roque, 410km northeast of Bogota.
Survival 'impossible'
Carlos Garcia, head firefighter leading the rescue attempt, said: "It is impossible that those still in the mine are alive due to the high amount of poisonous gas in the mine shafts. It would be a miracle if they are alive."
Rescue workers face the danger of more explosions due to combustible gasses, local officials said.
"I can't believe what is happening [and] I would not wish this on anyone"

Jorge Vergara, brother of two of the trapped miners
Jorge Vergara, brother of two of the trapped miners, said: "I can't believe what is happening. I would not wish this on anyone."
Victims' family members and friends remained gathered at the entrance of the mine.
Truckloads of police and soldiers arrived on Sunday morning in preparation for a possible visit from Alvaro Uribe, the president.
La Preciosa produces coal for domestic consumption.
A similar accident occurred in the town of El Zulia, also in the mountainous province of Norte de Santander, when a coal mine explosion killed 15 people in 2001.
Norte de Santander is an area violently contested by armed groups fighting a decades-old guerrilla war. Both groups, branded terrorists by Washington, fight over control of cocaine smuggling routes from the province into neighbouring Venezuela.