Rescuers in China entered a mine Saturday where 153 workers have been trapped for nearly a week but have so far not detected any further signs of life.
Chinese media reported that a team of 13 rescuers, including six divers, entered a flooded mine in China's Shanxi Province after tapping noises were heard Friday afternoon.
Within a few hours, some of the rescuers returned to the surface and described the situation as challenging.
Rescue teams lowered a listening device through a drill pipe hoping to hear voices or other sounds of life, but nothing new had been heard as of noon Saturday local time.
At least 3,000 rescuers have been working to pump water out of the mine since the accident. They have lowered buckets down a narrow hole with pens, paper and food supplies.
The miners became trapped when water filled the shaft at the Wangjialing mine Sunday. More than 100 other workers were able to escape the floodwaters.
Reports say the water level inside the mine has dropped by about five meters since last Sunday, but the miners' survival would depend on access to clean water and air to breathe.
Officials have yet to declare a cause of the accident, but a preliminary investigation says workers had likely penetrated old or abandoned mines that had accumulated water.
China's coal mines are among the most dangerous in the world.
Official statistics indicate more than 2,600 people were killed in mine accidents in China during 2009.
Some information for this report was provided by AFP and AP.