At least 31 miners are missing and feared dead following a powerful explosion Saturday in a coal mine in northeast Colombia, authorities said. The blast burying the miners took place around 10 a.m. (1500 GMT) at La Preciosa mine located in the remote hamlet of San Roque, 410 kilometers (255 miles) northeast of Bogota. "There is a lot of gas inside and we're in the process of trying to get it out to see if rescue crews can go inside," Fernando Rosales, director of civil defense in Norte de Santander state, told The Associated Press from outside the mine. Rosales said the 31 missing miners were buried in two separate underground tunnels. The explosion was caused by "some spark and the gas that was inside" the mine, he said. Rosales said that although emergency crews have not been able to enter the mine's interior, hopes of finding the miners alive is "discouraging" because of the considerable damage done to the mine and the fact that crews have not yet been able to release the trapped gases. Many mines in this Andean nation are makeshift affairs with few or no safety procedures.