The explosion occurred inside Shijar Vietnam Co., Ltd at around 7 a.m. Vi Van Nguyet, 27, and Dang Thanh Thai, 22, died on the spot.
One hour earlier, Nguyet, Thai and two other workers reportedly alerted a foreign expert to the unusually high temperature inside the kiln, but the expert asked them to keep working and use a two-meter iron stick to check the burning coal.
Thai and Nguyet were reportedly sitting on the mouth of the kiln when it exploded. They were thrown dozens of meters away by the blast.
Local authorities are still investigating.