But because of poor ventilation , gas poured into the main tunnel and triggered an explosion that shook 28 of the 30 mining platforms in operation . Chinese officials blamed poor ventilation and inadequate ventilation for an explosion . It killed 104 and injured 100 others . Last year , 3,200 people were killed in mine accidents , state media said . Four miners still trapped underground , state media reported .
Chinese officials blamed poor ventilation and inadequate ventilation for an explosion . It killed 104 and injured 100 others . Last year , 3,200 people were killed in mine accidents , state media said . Four miners still trapped underground , state media reported .