A packed train derailed inside a tunnel in eastern Taiwan on Friday leaving at least 41 people dead, according to the rescue agency and local media reports.
Officials said the accident could have been caused by a maintenance vehicle sliding down an embankment and striking the train before it entered the tunnel near the coastal city of Hualien.
Tsai Ing-wen, the President of Taiwan, called it a "heartbreaking incident" in a tweet this morning.
"The top priority now is to rescue the stranded people", her office said in a statement. Media showed pictures of survivors being led out of the tunnel.
"Around four people are without life signs", the Central Emergency Operation Center said in a statement, adding rescuers were trying to get to four carriages inside the tunnel that were badly damaged and hard to access.
The Central Emergency Operation Center gave a slightly lower suspected death toll of 26 people showing "no signs of life".
Another live broadcast by local news network UDN showed at least two undamaged train carriages outside the tunnel with rescuers helping passengers escape.
One of the biggest accidents in Taiwan's railway history happened when an express train derailed in a tunnel after hitting a truck.
The fire department added that between 80 and 100 passengers were evacuated from the train's first four cars.
The train had only partially emerged from a tunnel, and with much of it still inside, many escaping passengers were forced to scramble out of doors and windows and scale the sides of the train to walk along the roof to safety. As many as 350 people, many of them tourists, were onboard the train when the mishap occurred.
During the festival, people return to ancestral villages to tidy up the graves of their relatives and make offerings.
Taiwan's eastern railway line is usually a popular tourist draw down its dramatic and less populated eastern coastline.
In 2018, 18 people died and 175 were injured when a train derailed in the island's northeast.
The driver of the eight-carriage train was later charged with negligent homicide.
More than 40 people have already been taken to hospital and others injured are in the process of being taken to hospital, with around 70 reported trapped in train carriages. In 1981, 30 were killed in a collision in northern Taiwan.