Two trains have collided head-on on a level crossing north-west of Copenhagen, leaving five people critically hurt and 13 others with less serious injuries, medical officials say.

The trains were travelling early on Thursday on a line linking the towns of Hillerød and Kagerup in the North Zealand area of north-east Denmark, with a total of 37 people on board, according to police.

Tim Ole Simonsen of the Greater Copenhagen fire department was unable to say what led to the crash but told Danish TV that all the injured had been taken to hospital by air or by ambulance.

Local mayor Trine Egetved expressed her shock at the accident, stating the local track is heavily utilized by residents. Many Gribskov residents, workers, and students depend on it.

The incident occurred at 06:29 local time (05:29 BST) on Thursday, and fire and rescue teams were alerted immediately. Egetved remarked on the alarming nature of such a collision, emphasizing the importance of preventing future occurrences.

In a statement, Prime Minister Mette Frederiksen voiced her concern regarding the devastating nature of the accident.

Denmark's Accident Investigation Board has initiated an investigation, and the cause of the crash remains unknown, with possibilities including signaling failures or human error being explored.

Reports suggest one train driver quickly applied the brakes and assisted in evacuating passengers, as several members of train staff were also injured. The safety director at Lokaltog described the collision as one of the worst possible scenarios in the train industry, emphasizing the need for data collection and thorough investigation.

Rail accidents are relatively rare in Denmark, with experts indicating potential issues regarding updated safety systems on the Gribskov line.