The multiple collisions occurred in heavy fog on the Seoul-bound lane of a bridge that forms part of the main expressway linking Incheon airport with the capital.
The pile-up involving 105 vehicles appeared to have started when a limousine ran into the back of a car, an Incheon police station spokesman said.
The foggy conditions meant drivers could only see 15 meters (50 feet) in front of them, he said, adding that 63 people, including 18 foreigners, were injured.
The injured included seven Chinese, three Thai, two Vietnamese and two Filipino visitors, Yonhap news agency said. The other four foreign nationals were from Japan, Russia, Bangladesh and Switzerland.
TV footage showed emergency rescue workers trying to access the mass of twisted and crumpled wrecks on the fog-covered bridge.
“I heard a series of bangs in front of me. Then I was rear-ended by a following car. I felt my car turning around and hitting a protection rail. I then lost consciousness,” cab driver Yoo Sang-Young told Yonhap news agency.
Another driver was quoted as saying the thick fog had prevented him from seeing the danger ahead.
“I slowed down but still rammed into the cars piled up in front of me,” he said. (AFP)