"There were 31 men in the mine at the time of the explosions," Fernando Rosales, head of the province's civil defense corps, told Reuters.

Rescue and recovery attempts, complicated by deadly gases remaining in the mine shafts, resumed at daybreak on Sunday after being suspended the night before. The bodies of 18 miners were recovered from the La Peciosa mine near the town of Sardinata while 13 others were trapped underground.

 "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," Carlos Garcia, head firefighter leading the rescue attempt, told Reuters.

Rescue workers face the danger of more explosions due to combustible gasses, local officials said.

"I can't believe what is happening. I would not wish this on anyone," said Jorge Vergara, brother of two of the trapped miners, sadness etched on his face as he stood at the entrance of the mine with other victims' family members and friends.