Bogota, March 16 : At least 11 people were killed and 10 others remained missing after an explosion ripped through a coal mine in Colombia's Cundinamarca, local authorities said. "We are making every effort with the Cundinamarca government to rescue the trapped people alive," President Gustavo Petro said on Twitter late Wednesday. "The nation, department, municipality and relief agencies continue working to rescue the ten miners who are still trapped. The Ubate hospital is treating nine miners, six of whom have already been discharged," Cundinamarca governor Nicolas Garcia Bustos said on social media. He added that rescue teams were working to locate the missing miners at the risk of a secondary explosion, which could be caused by gas accumulation. When the incident occurred, 30 miners were inside the five interconnected 900-meter-deep mines for carbon. Fortunately, seven escaped on their own, said Alvaro Farfan, commander of the Cundinamarca Fire Department. Farfan said that rescuers were trying to establish communication with the trapped miners to determine their state of health and facilitate the rescue. Family members of the missing miners gathered outside the coal mine, while the relatives of the deceased received psychological aid, Cundinamarca's government said. /IANS