SEOUL - Casualties were feared in South Korea's construction site collapse, Yonhap news agency said Friday citing the police.

The collapse occurred at the underground construction site in Gwangmyeong, just south of the capital Seoul, around 3:13 pm local time (0613 GMT).

Among 17 workers at the site, one was trapped underground while one excavator driver remained missing.

With the collapse, ground roads and nearby commercial facilities were damaged, but no additional casualties were reported.

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Earlier in the day, a risk of collapse was reported as a number of cracks were found in columns of the underground tunnel that was under construction.

At the time of the collapse, traffic on the surrounding roads was completely blocked.