The door of an LRT train opened mid-journey on Friday morning, much to the alarm of passengers on board.
The incident coincided with a five-hour service disruption on the Bukit Panjang LRT system, from 5.50am to about 11am, that same morning when only one loop was in operation.
The Sunday Times understands that the disruption was due to a signalling fault.
A photo of the incident was posted on social media platforms Twitter and Facebook by 16-year-old student Dilla Damitra. She claimed the incident happened at 6.46am when the train was travelling from Bukit Panjang to Senja.
When contacted, she told The Sunday Times: "I was definitely shocked. Luckily no one was standing by the door at the time."
Student Nurul Nadhirah, 15, posted a second photo of the open door in response to Ms Damitra's tweet.
She said that the train stopped abruptly and was stuck with the door open for about 20 minutes between Bukit Panjang and Senja stations.
"People stumbled and I could see fear in everyone's eyes, especially a young girl's. She skidded but was quickly pulled back by a lady," Ms Nurul said.
"I was scared because there were a few people standing near the doors and I was afraid they might fall out of the train."
Ms Nurul also claimed that passengers had problems accessing the emergency phone, which they later found was not working.
Ms Damitra said a woman eventually called SMRT on her mobile phone to report the problem.
An LRT staff member appeared soon after that to check the doors, and drove them to Senja station. At Senja station, the doors opened and closed repeatedly before most of the passengers alighted.
Ms Nurul, who attends West Spring Secondary School, was a few minutes late but she said her principal was informed that there was an LRT service disruption.
When contacted, SMRT said that its staff reacted quickly to the incident.
Mr Patrick Nathan, SMRT vice-president of corporate information and communications, said: "When our staff member was alerted to the incident, he quickly boarded the affected train-car to check that the passengers were safe, before closing the door and driving the train back to the station."
He added that SMRT was investigating the incident.