Authorities in Taiwan say Friday's deadly train crash occurred after a truck fell onto the tracks.
A train partially derailed in eastern Taiwan on Friday after being hit by an unmanned vehicle that had rolled down a hill, killing 48 people.
A live broadcast by UDN outside the tunnel showed a row of undamaged train carriages with rescuers helping passengers escape.
"At present it is suspected because the vehicle wasn't braked properly, it slid for around 20 metres along the site access road and entered the eastern trunk line", he added.
The express train was packed with around 350 people, many of whom were standing, as it carried tourists who were heading home at the start of the long weekend. No one was in the truck at the time.
Pictures published by local news website UDN showed the front of the train inside the tunnel had been pulverised into a twisted mesh of metal. An investigation has been launched, and Hualien police have interviewed one person, Weng said.
People further back in the train were able to walk away from the crash comparatively unscathed. Many Taiwanese are expected to be flocking to popular holiday areas on the east coast of the island.
"In response to a train derailment in Hualien, Taiwan, our emergency services have been fully mobilized to rescue & assist the passengers & railway staff affected", Taiwanese leader Tsai Ing-wen tweeted.
The crash came on the first day of the four-day Tomb Sweeping Festival, an annual religious holiday when people travel to their hometowns for family gatherings and to pay their respects at the graves of their ancestors. He said the speed of the train was not known.
And 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. They were treating minor wounds and offering lunches.
Volunteer rescue workers from the Tzu Chi Buddhist Foundation said children were among the dozens who escaped the train cars.
In 1991, a collision in western Taiwan killed 30 people and another crash a decade earlier also killed 30. Those were said to be the worst previous crashes on the rail system that dates from the late 19th century.
Some 70 passengers remain trapped inside the mangled carriages, while another 40 have been rushed to hospital, after the train crashed outside the city of Hualien on Friday.