A KTX bullet train en route to Busan from Seoul derailed in central South Korea on Wednesday, injuring some passengers, the operator said.

The Korea Railroad Corp. (KORAIL) and firefighters said the derailment occurred at 12:58 p.m., when the KTX-Sancheon train was entering a tunnel in Yeongdong of North Chungcheong Province, 214 kilometers south of Seoul.

One passenger car from the train went off the tracks near the Yeongdong Tunnel after being apparently hit by a steel structure that fell from the tunnel, they said, adding that some repair work was under way inside the tunnel at that time.

An unknown number of passengers suffered minor injuries from being struck by shards of glass from broken windows, they said.

Due to the accident, train operations on the Seoul-Busan line were delayed by more than one hour, they said, adding the exact cause of the derailment is under investigation. (Yonhap)