A passenger train in Taiwan partially derailed Friday, leaving at least 48 people dead and over 100 more injured in what a rail official said is the country’s worst-ever rail disaster.

The accident occurred near Taroko Gorge National Park on the first day of the nation’s four-day Tomb Sweeping Festival, a religious holiday when people travel to their hometowns for family gatherings and to pay respects at their ancestors’ graves. The wrecked train had been carrying more than 400 people and collided with an unmanned vehicle.