On Saturday, South Korea rescue workers withdrew a man from the subway construction site near the capital of Seoul.
Officials continued to search for another person who is believed to be trapped inside.
IM Gwang-Sik, an official in the Gwangmyeong City, said the survivors are about 98 feet below the rubble for approximately 13 hours.
The survivor was aware when he was found and transferred to a nearby hospital.
Gwangmyeong city authorities withdrew the workers earlier from the construction site and stopped traffic in the area after receiving reports that the ventilation column was at risk of collapse.
The authorities were publishing dozens of rescue workers, vehicles and three cranes to search for the other factor that was still imperceptible.
