Police in Belgium are working to stop both Islamist extremists and what are described as "far-right hooligans" in the wake of last week's ISIS attack.
A group calling itself Casuals Against Terrorism gathered near an improvised memorial site Sunday evening. BBC reports that the hundreds of members dressed in black with face coverings, made Nazi salutes and harassed Muslim women.
One told AFP that they had come to support the attack's victims. "We are football hooligans, we don't have anything to do with politics."
Police eventually brought out water cannons to disperse the Casuals and arrested about ten.
Brussels Mayor Yvan Mayeur denounced their actions. "I am appalled by what is happening, to learn that such thugs have come to provoke residents at the site of their memorial," he said.
Prime Minister Charles Michel added that it is "highly inappropriate that protesters have disrupted the peaceful reflection at the Bourse (stock exchange)."
At the same time, authorities raided 13 sites in the country as part of their follow up investigations into Islamists still poised to carry out attacks. Dutch police also arrested a French national on suspicion of planning an attack in France.
Last Tuesday ISIS bombed the Zaventem airport and a subway station in Brussels. The attacks killed 28 people and wounded many more.