The incident led to a delay along the East-West Line - one of two faults which hit Singapore's train system on Wednesday morning. Train service on the North-South Line was also delayed during the evening peak hour.
Here's a timeline of events:
8.18am: A train heading in the direction of Tuas Link station stalled at Joo Koon station.
8.19am: A second train stopped behind the first faulty train. A minute later, the second train "moved forward unexpectedly" and collided with the first train.
8.25am: SMRT advised commuters via Twitter that there will be a 20-minute delay along the East-West Line between Jurong East and Joo Koon stations due to a train fault at Joo Koon station.
8.26am: Facebook user Mei Anne said she was on a train that collided with the stationary one, and was hurt in the incident.
8.33am: SCDF said it was alerted to an incident near Joo Koon MRT station.
8.37am: SMRT revised its announcement, informing commuters travelling between Jurong East and Tuas Link stations that their commute will be extended by 30 minutes.
9.26am: The train operator said the 30-minute delay affected commuters travelling between Queenstown and Tuas Link stations.
9.58am: Passengers travelling between Jurong East and Tuas Link stations can expect a 15-minute delay, said SMRT.
10.31am: In another update on Twitter, SMRT asked those travelling between Boon Lay and Tuas Link stations to expect an extra 10 minutes during their commute.
10.42am: SCDF issued a statement on Facebook, saying 23 passengers have been taken to hospital - most of them with minor injuries.
11.05am: The platform for trains travelling towards Tuas Link was partially cordoned off.
11.12am: SMRT and the Land Transport Authority (LTA) issued a joint statement confirming the incident, saying they are investigating. They added that 23 passengers and two SMRT staff sustained "light to moderate" injuries and were taken to Ng Teng Fong Hospital, as well as National University Hospital.
Noon: The trains were still on the platform. Train services were slow as the platform for trains travelling towards Tuas Link was cordoned off.
12.29pm: More than 15 SMRT staff wearing bright orange vests were seen on the platform near the affected trains.
2pm: SMRT issued an update on Facebook that train service will be suspended for two hours between Joo Koon and Tuas Link stations in both directions. This is to "facilitate the recovery" of the two trains that were involved in the collision, said SMRT.
3.21pm: One of the trains involved in the collision was pulled away in the direction of Tuas Link MRT station.
4.06pm: The second train involved was moved off.
4.14pm: LTA and SMRT updated the number of people injured to 28, including three walk-ins at Ng Teng Fong General Hospital.
Out of the 15 people sent to the National University Hospital, one declined treatment and returned home while 13 of those who received treatment have been discharged.
One passenger is currently warded for observation.
LTA and SMRT added that out of the 13 injured at Ng Teng Fong General Hospital, nine were treated and discharged, two are being treated, and two others are warded for observation.
5.15pm: SMRT tweeted that train services between Boon Lay and Tuas Link have resumed "but are running slower". It also advised commuters to add 10 minutes travel time between Jurong East and Tuas Link.
11.24pm: LTA and SMRT updated the number of people injured to 29, including another walk-in from an injured passenger at around 7.30pm in the evening.
Of the 14 injured who were admitted to Ng Teng Fong General Hospital - including the new walk-in - 11 have been discharged and two remain warded for observation. The new patient is being treated.