Transportation safety officials in Taiwan have released video footage taken from the front of a train involved in a fatal accident last week.
The limited express derailed in a tunnel in Hualien County on Friday, killing 50 people and injuring more than 200.
The footage released by the Taiwan Transportation Safety Board on Tuesday shows the train hitting a truck that had slid down a hillside onto tracks near the tunnel.
The train's front car tilted after colliding with the truck, and hit the wall of the tunnel.
Board officials analyzed the train's operation system and found that the driver applied the emergency brakes five seconds after the train exited another tunnel before hitting the truck two seconds later.
The officials said the train was traveling 121 kilometers per hour at the time, and that its front car stopped about 320 meters into the tunnel.
They estimate that the truck slid onto the tracks about one minute before the collision.
The officials also plan to study the train's operation records and aerial photos to investigate the cause of the accident in detail.