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 the helicopter in front of the Royal Palace in Dam Square and emergency vehicles also inside the cordoned-off area.
Police are urging anyone with images of the incident to upload them as evidence.
