BRUSSELS — Some 1,500 people gathered in front of the courthouse in Brussels Sunday to silently honor the four victims of the previous day’s shooting in front of Belgium’s Jewish Museum.

Belgium’s secular umbrella organization, Centre d’action laïque (CAL), united Belgians from all ethnicities and religions and called for a show of support to the families of the victims and the Jewish community.

“There isn’t just one community that is affected, it is everyone,” said Henri Bartholomeeusen, the president of the CAL general assembly, before inviting the crowd to observe a few minutes of silence.

Politicians including Belgian Prime Minister Elio Di Rupo and Foreign Minister Didier Reynders called for vigilance against hatred in their speeches and attendees expressed anger and sadness over the events of Saturday.

‘We slowly get used to small anti-Semitic acts, anti-social acts, to fundamentalist speeches’

“We slowly get used to small anti-Semitic acts, anti-social acts, to fundamentalist speeches,”Bartholomeeusen told Belgian TV channel RTL.

Meanwhile, approximately 300 members of the Jewish community gathered outside the Belgium Jewish Museum on Sunday evening to recite the Kaddish prayer for the dead and light candles at the scene.

Despite the day’s elections to the European Parliament, a strong showing of key politicians attended the silent protest.

Earlier Sunday, Joelle Milquet the deputy prime minister and minister of internal affairs, met with leaders of the Jewish community, the police and the crisis center to discuss future security measures for Belgium’s Jewish community centers.

The Jewish community has expressed a desire to “continue their activity” as normal. Schools, synagogues, cultural centers and other Jewish community centers will operate as usual — under reinforced security and permanent police protection.

On Sunday, the deadly attack claimed its fourth victim as Alexandre Strens, a young man who was critically injured by gunshot died of his wounds. An Israeli couple and a French woman were killed at the scene on Saturday.

Belgian prosecutors on Sunday said they were looking for a lone suspect in the lethal weekend shooting spree. Deputy prosecutor Ine Van Wymersch said the suspect “probably acted alone, was armed and well prepared.”

Police had detained one suspect late Saturday but he was soon released and is now considered a witness. A motive was not yet given, but the government has said it had the hallmarks of an anti-Semitic attack.

A survey published earlier this month by the Anti-Defamation League found that 27 percent of Belgian adults harbor anti-Semitic attitudes.

AP contributed to this report.