Two trains collided head-on at a level crossing northwest of Copenhagen on Thursday, leaving four people critically injured and 13 others requiring hospital treatment, according to officials.

The trains were traveling on a line connecting the towns of Hillerød and Kagerup in the North Zealand area of northeastern Denmark. Tim Ole Simonsen of the Greater Copenhagen fire department could not specify the cause of the crash but told Danish TV that all injured had been transported to hospital by air or ambulance.

Local mayor Trine Egetved said she was deeply shaken by the accident. Public broadcaster DR aired images of two yellow and gray trains with visible front-end damage facing each other in a wooded area.

Frederiksborg Fire and Rescue reported that they were alerted to the accident at approximately 06:30 local time on Thursday. Egetved, mayor of Gribskov municipality, stated that those with critical injuries had been flown to the National Hospital in Copenhagen.

Rail accidents are rare in Denmark. One expert suggested that one of the train drivers may have ended up on the wrong line by overriding a stop signal as the train left a local station. The Gribskov line is not believed to have been updated with an automated safety system. Egetved told DR that it was shocking that two trains could collide head-on and that measures must be taken to prevent a recurrence.

Source: www.bbc.com