A 400-strong group of demonstrators in central Brussels protesting last week's terror attacks were met by riot police and water cannons Sunday. The protesters stormed the Place de la Bourse, a square where Belgians have been paying tribute to the victims at a makeshift memorial, and 12 of them were arrested after explosive objects were hurled at officers, a spokesman for the Brussels police told NBC News.

Some of the protesters were thought to be members of the right-wing group called The Nation. Most were wearing black, while some wore masks. The massive group descended on the central square outside the Brussels  Stock Exchange and police fired a water cannon at least once to disperse the rowdy crowd, while those assembled at a peaceful rally cheered. As the self-declared fascists were pushed back by police, they shouted: “This is our home.”

A solidarity "march against fear" had originally been scheduled for Sunday, but the organizers agreed to postpone it after the Belgian government urged people not to attend, saying police resources were already stretched. "We understand fully the emotions," Interior Minister Jan Jambon said in making the appeal on Saturday, according to CBC News. "We understand that everyone wants to express these feelings."

Suicide bombings targeting Brussels Airport and a city metro station killed 31 people Tuesday, including three of the attackers, while wounding hundreds more. The Islamic State group, also known as ISIS or ISIL, has claimed responsibility for the triple bombings.

European security agencies are searching for at least eight suspects believed to have helped with the bombings in Brussels as well as the Nov. 13 attacks in Paris. The suspects had been in contact with Abdelhamid Abaaoud, the alleged mastermind behind the Paris attacks who was killed by French police in a shootout Nov. 18, and Salah Abdeslam, the prime surviving suspect of the Paris attacks, who was arrested in Brussels earlier this month, Die Welt am Sonntag newspaper in Germany reported.