Thirty-three miners trapped in the Chinese colliery explosion were confirmed dead after 15 more bodies of missing miners were retrieved on Wednesday morning.A total of 35 workers were in the pit at the time of the accident just after 11.30 a.m. on Monday. Two escaped unharmed, leaving 33 trapped in the pit. The bodies of 18 miners were recovered on Tuesday afternoon.More than 80 rescuers retrieved the bodies from the Jinshangou Coal Mine pit, Xinhua news agency reported.An investigation into the cause of the accident is underway.Preliminary investigations showed the mine exceeded its mining boundaries, had insufficient and malfunctioning equipment, poor ventilation and management.