The accident took place on Tuesday morning at the factory in Dai Hong – Hoang Son Industrial Park in Tan Hong District of Tu Son Town, Bac Ninh Province, 30 km from Hanoi.
Witnesses said after a large blast, black smoke started billowing from smashed windows.
Shortly after, many workers rushed out of the factory with burned clothes.
By 11:22 a.m., 34 staff had been taken to a medical center around three km away. Seven suffered severe burns and were transfered to larger hospitals.
Police are looking into the cause of the explosion.
The factory of Seojin Automotive Co., Ltd specializes in producing electronic components for smartphones and computers, as well as electric ovens, and transceivers. It is a supplier of electronics giant Samsung.