Four people were killed in the shooting at the museum's lobby, including a couple from Tel Aviv: Emanuel and Miriam Riva. A third casualty was a French volunteer at the museum, a woman in her 60s.
Belgium's Interior Minister Joelle Milquet said following the shooting, "It's still too early to confirm whether it's a terrorist or an anti-Semitic attack. All lines of investigation are still open."
"I find it hard to believe that the murder was not an anti-Semitic attack," said Rabbi Gigi, who also serves as the representative of the Conference of European Rabbis in the European Union institutions in Brussels.
"We are waiting for an official statement from the authorities on what happened there, and whether they have laid their hands on the despicable murderers."
Rabbi Gigi added, "We are entering a tough period in Europe in general and in Brussels in particular, and we expect the authorities to address anti-Semitic phenomena, even if they are expressed in words, like a terror attack on Jews. There is no room for tolerance and mercy."
Rabbi Menachem Margolin, the Brussels-based general director of the European Jewish Association (EJA), said the attack was predictable and that the condemnations were "nothing but a way to cleanse one's conscience," as anti-Semitism was raising its head in almost all of Belgium and throughout the EU member states.
"We in the midst of elections for the EU Parliament, and the overwhelming predictions as to the rise of fascist and anti-Semitic forces are staggering," Rabbi Margolin said Sunday. "It seems that Europe has not yet realized that democracies have to fend against this surge, with much more resolve.
"Those that do not bother to eradicate these anti-Semitic lesions within themselves, those that exercise understanding and forgiveness to such terror attacks because of narrow political interests, will end up being victimized by the same nationalist anti-Semites," he added.
The EJA general director recently called on all EU member states to establish a pan-European taskforce in order to annihilate anti-Semitism, saying it should act decisively both in the security and enforcement level as well as in education.
The Conference of European Rabbis called the attack "a terrorist act for the purpose of intimidation in the capital of Europe on the day of the election of the European government, and the murderers' message is clear: There is no room for Jews in Europe."
The organization said in a statement that the rise in the power of anti-Semitic parties and the tolerance towards any type of anti-Semitism – whether it is expressed in anti-Israel sentiments or in restrictions on the Jewish religion – must stop.