Rescuers are working to remove a buildup of sludge from the primary mineshaft of a coal mine in south China's Guangxi Zhuang Autonomous Region, hoping to reach 19 workers who were stranded in the mine after it became flooded and collapsed on Saturday.

"The rescue work is moving along at a much quicker pace," said rescue worker Huang Xiangxiong.

However, a round of heavy rains that started at 3:30 p.m. Sunday may trigger more collapses or floods.

Huang and his colleagues have been working in the mineshaft on rotating 8-hour shifts.

"The density of the toxic gas in the mineshaft remains high, and we have to be wary of more collapses," Huang said.

Huang said that although he and his fellow rescue workers have been able to penetrate as far as 350 meters into the main shaft, they have not yet been able to reach the workers. The miners are believed to be stranded at a location 390 meters underground.

Huang and his colleagues met the surface of the mine's floodwaters when they hit 350 meters. "Our emergency rescue headquarters has laid out a network of 17 drainage pipes. We hope to remove the water soon," Huang said.

The collapse occurred around midday Saturday in the suburbs of the region's city of Heshan. Investigators said the collapse was caused by continuous heavy rains.

Recent downpours forced mining authorities to halt mine operations in the region between June 29 and July 1. Mining operations were resumed on Saturday.

Seventy-one miners were in the mine when the collapse occurred. Forty-nine managed to escape, while three others perished in the collapse. The bodies of the dead miners have been retrieved.

Saturday saw another major mine accident in southwest China's Guizhou Province, where 23 people remain trapped in a flooded mine. Floodwaters continued to pour into the mine on Sunday, despite round-the-clock efforts to drain the water.