Fourteen people were injured after one of the escalators at a subway station in South Korea suddenly started moving backwards, trampling passengers.

According to Yonhap news agency, the serious accident happened at 8:20 a.m. at Sunae subway station on the Bundang line (an area south of Seoul).

Video shows the upward escalator leading to exit 2 of Sunae Station on Bundang Line reversing suddenly and going backwards for several seconds, on Thursday.

3 people were sent to a hospital after sustaining injuries on the back and legs. 11 others sustained minor injuries. https://t.co/H3gvUoiByi pic.twitter.com/gZ49v9x08W

— The Korea Times (@koreatimescokr) June 8, 2023

Suddenly, the upward-facing escalator began to slide downward, lasting several seconds, according to local police and fire officials.

Three of the passengers who were on the stairs when the incident happened were taken to the hospital with back and leg injuries. Another 11 people were slightly injured, they were given first aid and left.

Local authorities are investigating the cause of the incident, but – as their representatives have stated – they do not consider it very likely that someone interfered with the manual control system and deliberately changed the direction of the escalator.