The sole survivor of an accident which killed 12 West Virginia miners has suffered major internal injuries and could be brain damaged, doctors say.
Residents of Sago have been shocked by the mine accident
Randal McCloy Jr, 27, was moved to Pittsburgh after being deprived of oxygen while trapped underground.
He has responded to treatment but remains in a coma with damage to his heart, kidneys, lungs and possibly his brain, Dr John Prescott told reporters.
The mine's owners have been criticised by families of the miners who died.
"Certainly Mr McCloy is going to have a tough course," Dr Prescott said, before he was transferred from hospital in Morganstown, West Virginia.
"We just don't know at this point how things will turn out."
As Mr McCloy fought for his life, it emerged that several of the doomed miners wrote notes for loved ones to assure them they did not suffer.
"The notes said they weren't suffering, they were just going to sleep," said Peggy Cohen, daughter of Fred Ware Jr.
Vital 12 hours
Mr McCloy, who had shown signs of brain function and had squeezed his wife's hand from his hospital bed, will undergo intensive oxygen treatment in Pittsburgh.
"Mr McCloy's organ systems have responded fairly well to the treatment he has received over the last 36 hours," said Dr Larry Roberts of West Virginia University Hospital.
Mr McCloy's mother (r) has waited at hospital for news on her son
"His left lung is no longer collapsed. But we have not seen the neurological improvements we would like to see."
Doctors suggested that Mr McCloy's slow neurological response could indicate that he has suffered brain damage.
The next 12 hours would prove crucial, reporters were told.
Randal McCloy was the only miner to survive from among a group of 13 trapped underground following an explosion on Monday at the mine in Sago, West Virginia.
The accident turned to tragedy when poor communication - blamed by the mine's president on out-dated equipment and a desire for good news among rescuers - led to widespread reports that all 13 miners had been rescued alive.
Families of those trapped and millions around the world thought for three hours that all were safe, until the grim reality actually emerged.
International Coal Group, the company which owns the Sago mine, expressed its regret on Wednesday for the communication problems.
Its president, Ben Hatfield, said they fully accepted the criticism over the manner in which they handled the matter.
The Sago Mine was cited for more than 40 alleged violations of federal mine health and safety rules during an 11-week review that ended in December, according to reports.