Instead of following the zigzag queue formed by retractable belt barriers, the passengers pushed their luggage carts through the gaps in an apparent attempt to reach the counters ahead of others.
'Daigou' traders suspected
Five similar incidents were reported in July. The passengers involved were believed to be "daigou," or small-scale traders who purchase discounted duty-free goods in bulk in South Korea and resell them in China and other Asian markets, according to Yonhap News Agency.
Several airline staff members were reportedly injured while attempting to guide the passengers back into the proper queue.
Airport steps up preventive measures
In response, airport officials have stepped up inspections across departure halls to help maintain order and improve safety for both travellers and employees.
The airport also attributed the heavier congestion to airlines operating larger aircraft on major routes between Incheon and China, adding roughly 100 seats on some flights.
Officials said the situation had eased for a period after stricter enforcement in China led to a decline in the number of daigou traders travelling from South Korea. However, they added that check-in areas would continue to be closely monitored, as similar incidents could occur again.