Water flooded the mine late Tuesday while 143 people were working underground, RIA Novosti said. Four miners could not be located, while the rest escaped safely, officials said.
One body was recovered Thursday morning, and the bodies of two missing miners were found Friday and Saturday, RIA Novosti said. The fourth body was found Sunday morning.
Work at the mine has been suspended and rescuers are pumping water from the flooded areas, officials said.
RIA Novosti said a criminal case has been opened to investigate the violation of mining safety rules.
In 2010, 91 workers died in methane gas explosions, and in February 2013, a gas blast killed 18, RIA Novosti said.