A BTS Skytrain running with one of its doors wide open shocked passengers and drew heavy criticism after a video of the incident went viral online.

The video, originally posted on TikTok and then widely shared elsewhere, showed one door of the train open while it was between the Bang Chak and Punnawithi stations in Bangkok on Wednesday.

The incident unnerved many passengers and sparked criticism about safety measures taken by the operator.

Bangkok Mass Transit System Plc on Thursday apologised for the incident. It said the door had developed a problem on Wednesday, but did not say what the problem was.

Staff in charge of train control alerted those in the control centre to send staff to stand near the door to stop passengers from getting close to it. The problem was fixed when the train arrived at the next station.