THE LONGWALL SHEARER WAS STOPPED AT 19 SHIELD WHILE WORKERS BROKE UP ROCKS FROM ATOP THE PONTOONS OF THE SHIELDS BETWEEN 5 & 14 SHIELD. AFTER THE SHEARER BEGAN CUTTING AGAIN HARD BOTTOM WAS BEING REMOVED. A BLUE AND ORANGE FLAME ABOUT 3' FROM THE ROOF NEAR 19 SHIELD WAS OBSERVED. APPARENTLY THE IGNITION WAS SPARKED WHEN THE TAIL DRUM CUTTING THE BOTTOM IGNITED METHANE.