An ambulance enters the main gate of Hanwha Aerospace's factory in Daejeon, Monday, after a deadly explosion at the site earlier in the day. Yonhap

An explosion and fire at a Hanwha Aerospace plant in Daejeon killed five workers and injured two others, authorities said Monday.

Police and fire officials said the explosion occurred at 10:59 a.m., and is believed to have originated in a laboratory where the seven workers were conducting cleaning operations involving explosive materials.

The five victims died at the scene, where a blaze also broke out, while the two injured workers managed to escape on their own.

One of them suffered severe burns over most of the body and remained hospitalized, while the other sustained minor injuries and was treated before being discharged.