Gun killings are rare in Utrecht, but as of Monday afternoon three people were killed with five others wounded.
"We expect a terror motive. Our thoughts are with the next of kin and the witnesses of this horrific event," said Utrecht Mayor Jan van Zanen.
City police arrested two people who might be connected to the shooting. Police identified one of the suspects as Gökmen Tanis, a 37 year old man born in Turkey, who was on a tram near the 24 Oktoberplein station where the shooting occurred.
The department released a photo of Tanis and warned the public not to approach him.
King Willem-Alexander and Queen Máxima of the Netherlands released a statement shortly after the attack.