By Jeanny Yu and Cindy Wang

Taiwan has stepped up its investigation into its deadliest train accident in seven decades that has killed 50 people and injured more than 100.

Hualien police, Taiwan

Investigators have applied to detain the driver of the crane truck that collided with the train as it was about to enter a tunnel, Central News Agency reported, citing an interview with a local investigator. Police and investigators are still investigating and collecting evidence at the site, the agency said.

Preliminary assessments showed that the truck fell from a position above the railway, according to the Transportation Safety Board. Investigators suspect that the driver of the truck, who wasn’t in it when the crash took place, didn’t engage the hand brake before parking the vehicle at a work site servicing a separate rail line on a hill adjacent to the tunnel, the Taipei Times reported.

The eight-coach Taroko Express crashed at the tunnel in Hualien County on Friday. There were more than 490 passengers and four staff on the train and the death count currently stands at 50.

Flags in Taiwan are being lowered to half-mast for three days starting from Saturday, according to statement from the Cabinet. Countries including the U.S. have offered their condolences.

The Taiwan Railways Administration is taking away the carriages outside the tunnel, with those inside difficult to remove for now, according to CNA. The government hopes to resume the line’s operation sooner than an earlier estimate of seven days, the agency said, citing Transportation Minister Lin Chia-lung.

*Source: Bloomberg L.P.