SEOUL, South Korea — At least 38 people were killed Wednesday when one of South Korea’s worst fires in years broke out at a construction site near the capital, officials said.

They said the death toll could rise because more people could be trapped inside the warehouse that was under construction in Icheon, just south of Seoul.

The blaze erupted early in the afternoon and hundreds of firefighters took several hours to put it out. Images from the scene showed several firetrucks and more than a dozen ambulances surrounding the badly damaged structure, which was completely blackened and writhed on one side. Rescue workers in white protective suits were seen carrying out victims in body bags.

Eight construction workers were being treated for serious injuries at nearby hospitals, while two others were slightly hurt. Officials said about 30 workers managed to escape but at least one was unaccounted for.

Officials were investigating the cause of the fire, which was possibly triggered by an explosion while workers were working on an underground level at the site.

“There was no clothing left (on the workers) at all,” said Seo Seung-hyun, head of the Icheon fire department. “We presume that an ignition of oil mist caused an explosion and that the sudden combustion gave the workers no chance to escape.”

Seo said victims who died on other floors likely inhaled toxic gas. He said more than 400 firefighters and rescue workers and about 120 vehicles were deployed to the scene.

South Korean President Moon Jae-in called for officials to mobilize “all available resources” in the search and rescue operation, while Prime Minster Chung Sye-kyun, the country’s No. 2 official, visited the site to inspect the efforts.

South Korea, one of Asia’s richest economies, has struggled for decades to improve safety standards and change widespread attitudes that treat safety as subservient to economic progress and convenience.

Icheon was the site of another massive fire in 2008 when 40 workers died at a refrigerated warehouse.

Forty-six people died in 2018 when a fire ripped through a small hospital with no sprinkler systems in the southern city of Miryang.