The accident happened Monday at a mine operated by the Hon Gai Coal Company, a unit of Vietnam’s state coal miner Vinacomin, VNExpress news site said.
Early Tuesday morning a rescue team pulled out the bodies of the miners, who were aged between 23 and 47 years old.
According to disaster authorities, heavy rainfall was reported in Ha Long City, in northern Quang Ninh province, at the time of the accident.
The torrential rains caused landslides, and several homes were flooded.
Other parts of the country’s north have also experienced heavy rain for days, triggering flash floods and landslides.
On the outskirts of Hanoi, several communities have been living in floodwater for a week.
Scientists have warned that extreme weather events globally are becoming more intense and frequent due to climate change.
Deadly mining accidents are not infrequent in Vietnam, which despite ramping up its green credentials still relies heavily on coal-fired power plants.
Seven others have died in mine accidents in Quang Ninh province since April.
Last year, accidents claimed at least 10 workers’ lives at Vietnam’s state-run coal and mining group, local reports said.