A small passenger ferry has capsized after it collided with a German cargo ship in a busy shipping canal 30 kilometres south of Amsterdam.
Firefighters, divers, a helicopter and a boat with thermal imaging cameras have been called in to search for the ferry captain, who is missing.
It happened near the city of Utrecht.
The 72 kilometre canal links Amsterdam to the Rhine. It is a major European waterway which has a strong current and is about 100 metres wide.
Police said the two crew on the German-registered freight vessel were being held for questioning. Both have tested negative for alcohol.
The collision happened at 4.00 am local time, and there are not thought to have been any passengers on the ferry.