Bulldozers and trucks on Friday continued to dump concrete slabs, metal rods and rocks into the main shaft of the Zapadnaya mine in the Rostov region to try and stop icy water from filling any more of its tunnels, nearly a kilometre below the surface.
From a neighbouring mine, other miners began to hollow out a passageway to the place where their 46 co-workers could have taken refuge from numbing water that rushed into Zapadnaya late on Thursday afternoon.
But the fate of the 46 miners remained unknown. Authorities still had not established contact with them and could only hope they were still alive. Among those trapped inside was Vasily Avdeev, who was named director of the mine only days ago.
More than 24 hours after icy water first gushed into the mine where 71 men worked inside, chances of rescuing those still trapped lessened by the minute.
The location of the trapped miners
"There is still a chance to save them... God willing 50%," Igor Kulikov, a miner who had managed to scramble out, said.
Others said that some of the shafts in Zapadnaya ran at an angle and that the trapped men could survive for several days if they had managed to reach these.
But authorities were still clueless as to the location of the trapped men.
"We have established the approximate place where the people are," Sergei Nazarov, deputy governor of the Rostov region, said, adding, "but, I emphasise that it's only approximate."
Nazarov said it could take a day to fill the mine's main shaft with debris to stop more water getting in and as many as two days to drill tunnels from neighbouring mines.
The accident occurred at 5:00 pm (1300 GMT) on Thursday, with authorities speculating that an underground pool of water, which had formed above the mine, broke through.
Some 25 miners who managed to scramble to the surface described the numbing water rushing in as a "roaring current."
"There is still a chance to save them... God willing 50%"
"We barely got out of there," one of them, Kulikov, said. "The people who were in the lower levels got trapped."
"The water flooded in without warning," said Konstantin Koreoshenko. "All of a sudden, we were up to our necks in water. It knocked you off your feet."
Anxious relatives rushed to the mine headquarters to scour the typed posted lists of those who were inside the mine at the time of the accident and of those who had managed to escape. Some sat quietly, their faces tense, some wiped away tears.
The accident was the second one at the mine this year. In February, water broke through to the mine, but there were no people inside at the time, the news agency said.
Mines in Russia are notorious for their poor safety record, and fatal accidents are common.