In a collision between two cars in the tunnel of the Eider Barrage, four people were seriously injured on Thursday.
That said a spokesman for the regional control center West.
At first there was no further information about the cause of the accident in the Dithmarschen district or the identity of the injured.
According to media reports, the cars were thrown against the tunnel wall.
Wesselburen - The tunnel connects North Frisia with Dithmarschen.
dpa