A spokesperson for the Ministry of Justice and Security said that one prisoner started the shouting, encouraging other prisoners to join.

The prisoner who started the shouting was placed immediately in an isolation cell and discussions surrounding consequences to the other prisoners are underway, according to RTL Nieuws.

Source: Wikipedia / Mystro82 – https://nl.wikipedia.org/wiki/User:Mystro82

The director of National Monument Camp Vught, Jeroen van den Eijnde argues this shouting was prepared prior, NOS reports. He says, “There must have been windows open or maybe they were outside.”