Colombia : A Colombian mining agency says 20 miners are dead . NEW : The agency says 20 miners were killed . The blast happened near Colombia 's border with Venezuela . A build - up of methane gas may be to blame , governor says .
NEW : A Colombian mining agency says 20 miners are dead . NEW : The agency says six miners were injured . The blast happened near Colombia 's border with Venezuela . A build-up of methane gas may be to blame , governor says .