South Korean rescue workers said Saturday that the death toll in an auto parts factory fire in the central city of Daejeon has reached 14, after an explosion and flames injured dozens of others. The fire was reported at about 1:18 p.m. Friday, and officials said the response and searches continued into the weekend as crews worked to control the blaze and locate missing workers.

Officials said 25 people were seriously injured, but they did not immediately say whether any of those injuries were life-threatening. By Saturday morning, 28 people were hospitalized, and four patients had undergone surgeries for broken bones and other injuries, according to the city’s fire officials.

Thick gray smoke rose from the factory complex, with videos and photos showing some workers jumping from a building belonging to Anjun Industrial to escape. Fire officials said firefighters deployed more than 500 personnel, including firefighters, police and emergency responders, as they tried to contain the fire and conduct rescues after it began Friday afternoon.

Daedeok district fire chief Nam Deuk-woo said the blaze destroyed a factory building that firefighters initially could not enter because of fears it might collapse. Nam said crews began searches for missing workers late Friday after officials deployed unmanned firefighting robots to cool the structure and carried out a safety inspection before entering.

Officials reported that nine of the 14 dead were found in what they believed was a gym on the third floor, and three were found near a water tank on the second floor. Nam said all the missing workers had been accounted for after the latest recoveries.

South Korean President Lee Jae Myung visited the site Saturday afternoon. He met with relatives of the victims and called for safety measures intended to prevent a damaged structure from collapsing during search operations.

Nam said the cause was not immediately known, but he described signs that the blaze spread rapidly. He said witnesses reported an explosion and that firefighters focused on preventing the fire from spreading to an adjacent facility and isolating explosive chemicals at the plant. Nam said workers recovered more than 100 kilograms (220 pounds) of highly reactive chemicals from the site.

Fire officials also described the scale and equipment involved in the response. They said about 120 vehicles and pieces of equipment—including aircraft, an unmanned water cannon vehicle and two firefighting robots for hard-to-reach areas—were deployed, along with hundreds of personnel.