President Lee Jae Myung ordered the mobilisation of all available resources to deal with the fire and save lives, the presidential Blue House said in a statement.
The National Fire Agency said it was concerned the number of injuries could rise at the blaze in Daejeon, about 160km south of the capital Seoul.
Firefighters were struggling to contain the fire as one of the two buildings affected had collapsed, a fire official told Reuters.
Fire officials said the supplier is Anjun Industrial, which said on its website that it makes engine parts and it is a supplier for Hyundai Motor and Kia Corp among others.
Officials at Anjun were not immediately available for comment. REUTERS
