An aerial view of a burning sound barrier along northbound Second Gyeongin Expressway on Thursday. (Yonhap)

At least five people died and 37 people were injured as of 5 p.m. Thursday as a fire engulfed a soundproof tunnel on a highway in Gwacheon, southern Gyeonggi Province, on Thursday afternoon.

President Yoon Suk-yeol ordered the Interior Ministry and Health Ministry to conduct a thorough search at the scene of the incident to prevent more deaths. He also ordered an all-out inspection of the road structures like sound barriers to check whether the materials used are fire-prone, in a move to prevent the fire from repeating, according to a presidential office spokesperson.

Fire authorities earlier revealed that six were found dead, but later made a correction regarding the death toll.

The incident was first reported to the fire authorities at 1:49 p.m. on the eastbound Second Gyeongin Expressway near North Uiwang Interchange. Over 200 calls followed.

The fire gutted the hundreds of meters-long tunnel-shaped structure, covering a bridge that traverses an industrial complex called the Gwacheon Knowledge Information Town.

Forty-four cars were trapped under the structure along the road when the fire broke out, causing drivers to get out of their cars and run from the fire.

This photo provided by a third party shows a fire that engulfed a soundproof tunnel on the Second Gyeongin Expressway on Thursday. (Yonhap)

This aerial photo shows a scaffolding of a burnt soundproof tunnel along the Second Gyeongin Expressway on Thursday (Yonhap)

The crack of fire started with the collision of a cargo truck and a bus, which soon spread to the sound barrier.

Casualties include bus passengers. Among the injured, three are reported to be in critical condition with facial burns. The remaining 34 suffered minor injuries from inhaling toxic gas.

Fire authorities issued a second-stage emergency response order at 2:22 p.m. to mobilize firefighting apparatus from up to 14 fire stations, 10 minutes after the milder first-stage order was in place. So far, 94 apparatus including fire trucks were dispatched to the scene of the disaster with 219 firefighters.

Fire authorities said they damped down the flames at 3:18 p.m, and extinguished the fire at 4:12 p.m.

The fire department is also looking further into the degree of the damage and the cause of the fire.

Police mobilized over 240 police officers to block traffic from both directions near the site on the expressway connecting Yeongjongdo Island in Incheon and Seongnam, Gyeonggi Province, following the deadly incident. Police and Gwacheon Metropolitan Government public servants also blocked cars from accessing the road under the bridge within a one-kilometer range due to objects falling from the fire on the bridge.

A search operation is underway at the scene of the fire on the Second Gyeongin Expressway on Thursday. (Yonhap)