At least 18 people were injured on Saturday when an escalator at a shopping mall of Hong Kong’s Langham place suddenly reversed direction and increased speed.

Video footage shot by witnesses showed that an upwards escalator suddenly reversed and went downward at an obviously higher speed, leading to dozens of passengers losing their balance and tumbling down to the ground.

Several ambulances rushed to the scene and took the injured to nearby hospitals.

A man who suffered a head injury was in serious condition, according to police.

The contractor for maintaining the escalator, the Otis elevator company, has been asked to investigate the cause of the accident.