Rescue teams in China continued to work to save four miners trapped in an underground gypsum mine in eastern China on Monday. Chinese state media said rescue work is moving slowly to pull the men out after 10 days of being trapped.

China National Radio said that the men are trapped more than 200 meters below the surface. Because the ground is fragile, rescuers have managed to drill a path only 25 meters deep after more than 40 hours.

Rescuers using infrared cameras detected the survivors last Wednesday — five days after the cave-in.

The Dec. 25 mine collapse in Shandong province killed at least one person. Thirteen others are missing, and 11 made it to safety or were rescued earlier.

Rescuers initially believed they had found eight trapped survivors but were able to make contact with only four, the Associated Press reported.