COPENHAGEN, Denmark — Two trains collided in Denmark early Thursday, leaving five people critically injured in what police called a major incident.

The collision occurred around 6:30 a.m. near Hillerød, about 40 kilometers (25 miles) north of Copenhagen. Roughly a dozen other people have minor injuries, according to the Greater Copenhagen Fire Department.

There were 38 people aboard the two trains, according to a spokesperson for the North Zealand police.

Officials originally said four people were critically injured but revised that figure hours after the crash. It was not immediately clear whether the train’s drivers were among the victims.

Investigators are looking into what caused the collision, which occurred near a level crossing. Photos from the scene show the front ends of the trains smashed, though both remained upright on the tracks.

The mayor of the nearby town of Gribskov, Trine Egetved, in a post on Facebook, said some of the injured were flown to the hospital.

She said the crash occurred on a local rail line that’s used by many Gribskov residents, employees and schoolchildren.

No other details were available.