Tallmansville, W.Va. As the victims' families made plans for the first of the funerals, officials worked Friday to purge the Sago Mine of poisonous gases and allow investigators to determine what sparked the blast and how the miners spent their final hours.
Workers began drilling three ventilation holes into the mine. But International Coal Group chief executive officer Ben Hatfield said it could be days before the first investigators go in.
"There are so many things we don't know about what went wrong," Hatfield said. "We don't want to put any more people at risk until we know answers."
The Mine Safety and Health Administration appointed an eight-person team to investigate Monday's blast that killed one miner immediately and left 12 others trapped more than two miles inside. Only one miner was alive when they were found nearly 42 hours later, huddled together behind a plastic curtain erected to keep out deadly carbon monoxide.
Investigators said they are looking into all possibilities, including suspicions that lightning ignited naturally occurring methane gas or coal dust. Even before the blast, those were areas of concern at the mine, which had been cited for violations in 2005 regarding the ventilation plan to control dust and explosive gases.
The accident took place after the mine had been closed for the holiday weekend; the explosion was believed to have originated in an unused section of the mine.
Mine safety experts said gas can build up in a mine after just one day of idled operations, especially in the winter, when the barometric pressure drops.
The sole survivor's recollections could prove crucial. But 26-year-old Randal McCloy Jr., was believed to have brain damage from oxygen deprivation and remained in a medically induced coma Friday at the Pittsburgh hospital where he was moved a day earlier to receive intensive oxygen treatments.
Dr. Richard Shannon suggested rescuers reached McCloy just in time, because it appeared that in his last hour or so in the mine, he lost the ability to sneeze and cough, and his lungs began to fill with coal dust and the low-lying gases as he lay on his side.