Three coalminers suffocated to death Wednesday in the northern province of Quang Ninh.
Tran Minh Thanh, 37, Hoang Minh Duong, 27, and Bui Huy Thuc, 25, all employees of the Dong Vong Coal Company in Uong Bi City, entered the mine around 7:30 a.m. and did not come back out.
Thanh was a deputy foreman; Duong was a safety supervisor; and Thuc was a technician for the company.
Rescuers found the three dead men inside the mine after a two hour search.
Initial investigations showed the trio died of asphyxiation.
The case is being investigated further.