The accident occurred on Taiwan's eastern railway line near the coastal city of Hualien.Taipei, Taiwan:
A packed train derailed in a tunnel in eastern Taiwan on Friday at the start of a long holiday weekend with authorities saying at least four passengers appeared to be dead and dozens of others were injured.
President Tsai Ing-wen's office said she had ordered hospitals to prepare for a mass casualty event.
"The top priority now is to rescue the stranded people," her office said in a statement.
The accident occurred on Taiwan's eastern railway line around 9.30am (0130 GMT) near the coastal city of Hualien.
"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 difficult to access.
At least 27 people were sent to hospital and dozens were still trapped, the centre added.
Taiwan Railways Administration issued a separate statement saying "many" were without signs of life, citing the local fire department.
A brief video released by the centre inside the tunnel showed rescuers arriving on the scene and one twisted carriage door.
Another live broadcast by local news network UDN showed at least two undamaged train carriages outside the tunnel with rescuers helping passengers escape.
The eight-car train was making its way from Taipei to the southeastern city of Taitung and was carrying some 350 passengers.
The accident occurred at the start of the busy annual Tomb Sweeping festival, a long holiday weekend when Taiwan's roads and railways are usually packed.
Taiwan's eastern railway line is usually a popular tourist draw down its dramatic and less populated eastern coastline.
With the help of multiple tunnels and bridges, it winds its way through towering mountains and dramatic gorges before making its way down Huadong Valley.
The last major train derailment in Taiwan was in 2018 and left 18 people dead at the southern end of the same line.
The driver of the eight-carriage train was later charged with negligent homicide. More than 200 of the 366 people on board were also injured.
That crash was the island's worst since 1991, when 30 passengers were killed and 112 injured after two trains collided in Miaoli.
Thirty were also killed in 1981 after a truck collided with a passenger train at a level crossing and sent coaches over a bridge in Hsinchu.
In 2003, 17 died and 156 were injured after a train on the Alishan mountain railway plunged into a chasm at the side of the track.
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