A train has partially derailed in Taiwan after being hit by an unmanned vehicle that rolled down a hill, killing 48 people.

With the train still partly in a tunnel, survivors climbed out of windows and walked along the train’s roof to reach safety after the country’s deadliest railway disaster.

The crash occurred near the Toroko Gorge scenic area on the first day of a long holiday weekend when many people were using trains on Taiwan’s extensive rail system. The train had been carrying more than 400 people.

The National Fire Service confirmed the death toll, which included the train’s young, newly-married driver, and said all aboard had now been accounted for.

More than 100 people were injured, it said. Railways news officer Weng Hui-ping called the crash Taiwan’s deadliest rail disaster.

Mr Weng said a construction truck operated by the railway administration slid onto the track from a work site on the hillside above. No-one was in the truck at the time. He said the speed of the train was not known.

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.

Television footage and photos posted from the scene on the website of the official Central News Agency showed people climbing out of the open door of a carriage just outside the entrance to the tunnel. The inner wall of one carriage was pushed all the way into the adjacent seat.

Taiwan is a mountainous island, and most of its 24 million people live in the flatlands along the northern and western coasts that are home to most of the island’s farmland, biggest cities and high-tech industries. The lightly populated east is popular with tourists, many of whom travel there by train to avoid mountain roads.

An investigation has been launched into the crash, and there was no immediate word about any arrests.

In a tweet, Taiwanese President Tsai Ing-wen said emergency services “have been fully mobilised to rescue & assist the passengers & railway staff affected. We will continue to do everything we can to ensure their safety in the wake of this heartbreaking incident.”

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.

Taiwanese Premier Su Tseng-chang said the Railways Administration would be required to immediately conduct checks along other track lines to “prevent this from happening again”.