Groups of young Moroccan of around 40-80 men where roaming largest Utrecht shopping, Hoog Catharijne. They where blocking passages and some where harassing the shoppers (Eye witnes RigorMortis on the Dutch Fok blog: saw some grab a womans breast and ass). When police did an arrest, the different groups came together and a group of around 300 turned against the police. The police had to use batons and dogs to suppress the riots and to remove the youth from the shopping center. The police did 16 arrests.
Security personnel of the shopping center said that they always have 'feast' during Moslem feasts. But police said they did not know why the groups where in the shopping center and says they are investigating why they came there.
Sources: Utrechts Nieuws blad, Nieuws.nl, Nu.nl