[6][8] At 16:50 local time (UTC+8), a Puyuma express train, service 6432 from Shulin bound for Taitung, derailed on a curve with a radius of 300 metres (980 ft) when passing through the Xinma station in Yilan County, about 70 kilometres (43 mi) from Taipei.

[11] Survivors said that the driver applied the emergency brake multiple times before the incident, and another claimed that the train sped up after the curve.

Nevertheless, a report by Chinese-language Apple Daily Sunday found that Taiwanese trains were experiencing problems with the ATP system, citing anonymous sources from within the TRA.

The direct causes of the incident were found to be excessive speed in the curve and the disabling of the train protection system by the driver, in breach of relevant operating regulations.

Other staff involved in the incident, such as dispatchers and mechanics, were found not to be liable, and no evidence of corruption or neglect of duty by public officials was reported.

[26] In response to views that there were shortcomings in the initial investigation, the Taiwanese government converted the Aviation Safety Council (ASC), which previously only dealt with aviation accidents and incidents, into the comprehensive Taiwan Transportation Safety Board (TTSB), which also covers maritime and train accidents and incidents.

[27] President Tsai Ing-wen called the accident a "major tragedy" and directed the government and military to "step up" rescue efforts.

[30] In October 2021, the Yilan District Court sentenced the driver of the train to four years and six months imprisonment for negligent homicide.