At least 14 people were injured when an escalator at a busy South Korean subway station unexpectedly reversed direction, sending riders hurtling towards the ground.

Security footage captured the heart-stopping moment an escalator at the bustling Sunae station in Bundang, south of the capital of Seoul in Gyeonggi Province, went rogue during the Thursday morning rush-hour.

In the video, the automatic staircase, which is supposed to be going up, can be seen abruptly changing direction and going down instead, sending panicked riders plummeting downstairs and forming a pile of bodies at the foot of the escalator.

According to the Korea Herald, three individuals sustained serious injuries, while 11 others suffered minor injuries.

The elevator has been cordoned off after causing injury to 14 people (Picture: EPA)

The fire department said they plan to conduct a thorough investigation into the cause of the incident.

A maintenance company conducted a monthly inspection on the escalator in May and reported no issues.

Photos taken at the scene show first responders administering first aid to the victims, including a woman lying prostrate on the floor at Exit No. 2 at the station.

‘I thought people were filming a disaster movie after seeing so many people crowded around the fenced exit,’ a 68-year-old resident told the news outlet Korea JoongAng Daily.

The Railroad Special Judicial Police Unit under the Ministry of Land, Infrastructure and Transport will be in charge of getting to the bottom of the accident.  

‘Authorities, including the fire services, are currently looking into the cause of the accident,’ Gyeonggi Gov. Kim Dong-yeon tweeted Thursday. ‘We will investigate thoroughly so that no similar accidents occur.’

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14 people were crushed after a busy subway escalator suddenly changed direction.