(JTA) — Three people were arrested in connection with a firebomb attack on a synagogue in Gothenburg in southern Sweden.

The arrests were made early Sunday morning, hours after more than a dozen men hurled firebombs at the synagogue and locals marched in the city against the United States’ recognition of Jerusalem as Israel’s capital.

No one was injured in the Saturday night attack, which occurred while the synagogue was hosting a youth group program.

The Swedish Prosecution Authority announced the arrests, but no information was provided about the identities or motives of the people taken in.

On Saturday, protestors against the Jerusalem decision burned an Israeli flag in Stockholm. A day earlier, in Malmo, anti-Semitic slogans were shouted at a demonstration against the decision.

Security around synagogues in the Swedish capital of Stockholm was increased, Reuters reported citing the TT news agency.

Swedish Foreign Minister Margot Wallstrom on Sunday condemned the attack and calls for violence against Jews.

“The attack against the Synagogue in Gothenburg and calls for violence against Jews in Malmo are deplorable and totally unacceptable. Anti-Semitism, threats and violence have no place in our society,” she tweeted in English.

The attack against the Synagogue in Gothenburg and calls for violence against Jews in Malmö are deplorable and totally unacceptable. Anti-Semitism, threats and violence have no place in our society. — Margot Wallström (@margotwallstrom) December 10, 2017

The Jerusalem-based Simon Wiesenthal Center on Sunday in a statement denounced authorities in Sweden for their “serial refusal to act against anti-Semitism.”

Invoking the Saturday night attack against the synagogue in Gothenberg, Rabbi Abraham Cooper, the center’s associate dean, said in the statement: “what more will it take for this democracy to finally deploy the full weight of their law enforcement and judicial powers against anti-Semites and provide full protection for its Jewish citizens?”

World Jewish Congress CEO Robert Singer in a statement issued Sunday called on all European governments to “make this message infinitely clear and enforced”: “Anti-Semitic violence will never be tolerated.”

“We urge the Swedish authorities to take every measure possible to ensure the safety, security and well-being of its citizens. No person should ever have to live in fear or danger,” Singer also said.

In October, an administrative court in Gothenberg ordered that a neo-Nazi march scheduled to march past the synagogue on Yom Kippur be rerouted.

The Israeli-Jewish Congress in its reaction noted how the attack happened on the eve of International Human Rights Day, on Dec. 10, and called on European governments not to allow the use of Trump’s declaration to serve as a “pretext” for anti-Semitism.

Today, the IJC wrote, “such leadership is necessary more than ever!”

Dvir Maoz, the World Bnei Akiva youth movement’s emissary in Gothenburg, told JTA that the attack happened a little after 10 p.m. while youths from the local Jewish community were attending a party inside the synagogue complex. Looking outside from inside the synagogue lobby area, he said he saw in the corner of his eye “a ball of fire” approaching the building. “The guards saw it in the security cameras and called police right away. The children were stressed, it was the first time they had ever experienced a terrorist attack near them.”

The teenagers’ parents were called to take them home after police arrived at the scene and scanned the area to make sure it was safe to come out, he said. The culprits had already left by the time police arrived. The building did not sustain any substantial damage that he could see, Maoz added.

As they waited for police to arrive, the teenagers were taken down to the basement floor for safety, Laila Takolander, a member of the local Jewish community, told the Expressen daily.

“It is unconscionable that Jews are under attack on the streets of Europe, whether by terrorists hurling Molotov cocktails or openly and brazenly calling for the mass murder of Jews in Malmo, Vienna and Paris,” European Jewish Congress President Moshe Kantor said in a statement. “We call on European governments to take strong punitive action against those who perpetrated these acts and call for the immediate arrest of anyone who makes anyone making murderous chants.”

At other protest rallies about Jerusalem in Austria. France and Malmo, Sweden, participants chanted, respectively, in Arabic about an ancient massacre of Jews, freedom for Palestinian terrorists and shooting Jews.

Swedish Justice Minister Morgan Johansson wrote on Twitter: “[I]t is horrendous … to invoke violence against Jews,” and vowed to prosecute identifiable offenders.