A gunman has opened fire inside a tram and at several other locations in the Dutch city of Utrecht, authorities say.
Several people have been injured and one is feared to have died, media reports say.
Police say the gunman is still at large. Trains and trams have stopped running and schools have been asked to keep their doors closed.
Counter-terrorism police reportedly say the shooting "appears to be a terrorist attack".
Dutch anti-terrorism co-ordinator Pieter-Jaap Aalbersberg said all efforts were now focused on catching the gunman. He also said there could be more than one perpetrator.