A black box recording from a passing driver captures the moment a bridge collapsed during construction near Cheonan, South Chungcheong Province, Tuesday. Yonhap

At least three workers were killed while seven others were injured after a bridge collapsed during construction near Cheonan, a city in the central part of Korea, at 9:49 a.m., Tuesday.

Five 50-meter-long steel supports for the bridge collapsed during construction on the Seoul-Sejong highway.

Among the seven people with serious injuries, one suffered from cardiac arrest.

Fire authorities believe multiple workers have been buried in the accident at Dorim-ri, South Chungcheong Province, and are actively carrying out rescue operations at the scene by deploying rescue equipment and 172 personnel to the construction site where the bridge collapsed.

Acting President Choi Sang-mok urgently directed the Ministry of the Interior and Safety, the Ministry of Land, Infrastructure and Transport, the National Fire Agency, the National Police Agency and the South Chungcheong Provincial Government to deploy all available personnel and equipment for rescue efforts and search operations for missing individuals.

Seen is an aerial view of the bridge that collapsed during construction over Seoul-Sejong highway near Cheonan, South Chungcheong Province, Tuesday. Yonhap

The bridge varies in height, reaching a maximum of 52 meters, and the distance between the sections where the top plate fell is 210 meters.

The Seoul-Sejong highway, which runs 134 kilometers in total, is largely divided into two parts: a 72-kilometer metropolitan section from Anseong to Guri, Gyeonggi Province, and a 62-kilometer nonmetropolitan section between Sejong and Anseong.

The metropolitan section was opened on Jan. 1 and the entire section between Sejong and Anseong is expected to be completed by the end of 2026.

The site of the accident is included in the Sejong-Anseong section.

"All employees related to the construction site have been deployed and are focusing on dealing with the accident," said an official at Hyundai Engineering, which is in charge of construction in the area where the accident occurred. "We are assessing the details of the situation, such as how many field employees are employed by subcontractors."