Alarms about a serious train accident at Kagerup in northern Zealand came at 6:30 a.m. on Thursday.
It involved a head-on collision between two trains on a local train route between Hillerød and Kagerup.
18 people were injured - five of them critically, the police say. There are no reports of injured Swedes. Two of the injured are the train drivers.
There were a total of 37 passengers on board the two trains.
It is unclear what caused the accident. The route is single-track, which means that trains can only pass each other at stations.
The Danish Accident Investigation Board arrived at the accident site and began an investigation on Thursday morning.
