MAASSLUIS, Netherlands (AP) — Dutch police have detained dozens of protesters and arrested a man carrying a large knife in a bag amid tight security for the arrival of the Dutch Saint Nicholas.

The arrests Saturday came as thousands of families lined the historic harbor of Maassluis to welcome the character known as Sinterklaas, with children clambering up trees and street lights to get a better view.

The Sinterklaas celebration has in recent years been at the center of a debate about race in the Netherlands. That's because of his helper "Black Pete," who is often played by white people in blackface makeup.

Police spokeswoman Marjan Koert had no further details about the arrest of the armed man. Police tweeted that two busloads of protesters were detained in nearby Rotterdam.