Floodwaters kept rescuers from reaching 33 miners still trapped in a Chinese coal pit Tuesday, and the recovery of five bodies dimmed hopes of another miracle.
On Monday 115 survivors were pulled out after more than a week underground.
However, as rescue work stretched into its tenth day, toxic gas was also seeping into the mine.
Rescue headquarters' spokesman Liu Dezheng said gas was at an "impermissible" level.
"I can only say that we are exerting all efforts," Dezheng said when asked if he was hopeful for the survival of the remaining miners.
So far, there had not been any new signs of life from those still trapped, he said.
Rescuers were taking precautions to prevent explosions and to improve ventilation in the mine.
The trapped workers were in three different spots in the mining shafts that were so far inaccessible because of the flooding, China Central Television reported.
Pumping was hindered because of the narrowness of some parts of the underground passages, Dezheng said.
Dramatic rescue Monday
The grim outlook came after a dramatic breakthrough in the rescue effort Monday.
The 115 rescued miners had survived for eight days underground by eating sawdust and strapping themselves to the walls of the shafts with their belts to avoid drowning while they slept.
A total of 153 miners had been trapped since March 28, when workers digging tunnels broke into a water-filled abandoned shaft.
A preliminary investigation last week found the mine's managers ignored water leaks before the accident, the State Administration of Work Safety said.
Accidents killed 2,631 coal miners in China last year, down from 6,995 deaths in 2002, the most dangerous year on record, according to the State Administration of Coal Mine Safety.