Complex sentence: All of the 171 men working in the mine were killed in the series of three violent explosions and one worker, the leader of the rescue crew, died from carbon monoxide inhalation while attempting to reach the victims shortly after the explosion.
Split into simpler sentences: All of the 171 men working in the mine were killed in the series of three violent explosions. One worker, the leader of the rescue crew, died from carbon monoxide inhalation while attempting to reach the victims shortly after the explosion.