A bridge collapsed at an expressway construction site in S. Korea’s Anseong city on Tuesday, killing four workers and injuring six others, Yonhap News Agency reports citing authorities.

The accident occurred at around 9:50 a.m. in the city some 65 kilometers south of Seoul during construction on a section of the Seoul-Sejong expressway.

Several slabs placed on a pier fell to the ground, knocking off or burying 10 people working at the site. Of them, four died, five were seriously injured, and one sustained minor injuries, according to the fire authorities.

One of the four killed was pulled out from under the rubble at around 2:20 p.m., after which the authorities ended their rescue work.

The builder, Hyundai Engineering, apologized for the loss of lives and injuries.

"We are actively cooperating with the relevant authorities to ensure a swift site recovery and a thorough investigation into the exact cause of the accident," the company said in a statement.

The National Fire Agency had issued an order mobilizing firefighters to search for people missing in the accident.

Acting President Choi Sang-mok also gave emergency instructions to deploy all available resources and personnel for the rescue operation.