Five people have been injured following a stabbing in central Amsterdam, police say.
Dutch police say the area, which includes Dam Square, has been cordoned off and an emergency helicopter has been deployed.
A suspect has been arrested but the motive remains unclear, police say.
There are no details about the condition of the injured.
Video posted on social media shows a helicopter landing in front of the Royal Palace in Dam Square and emergency vehicles also inside the cordoned-off area.
Early images showed a person on a stretcher being loaded into the back of an ambulance.
A witness told the Dutch paper De Telegraaf that they suddenly heard an “icy scream” and after that panic broke out in the area.
A shop assistant also said that she heard a lot of shouting and screaming and that people started running in the direction of the incident, the paper reported.
Earlier, a police spokesperson told Dutch media there had been reports of a robbery.
Amsterdam’s mayor Femke Halsema was called away from a council meeting following the stabbing, local media also report.
Police are urging anyone with images of the incident to upload them as evidence.